Read the Spring 2008 Newsletter.

"Deciding on Human Plunder" End Notes

1. David S. Cloud, “Here’s Donny! In His Defense, a Show Is Born,” The New York Times, April 19, 2006, http://query.nytimes.com/gst/fullpage.html?res=9A02E6DD143FF93AA25757C0A9609C8B63
&scp=4&sq=%22I+decide+what%92s+best.%22&st=nyt

2. Inspired by the declaration, the cable television humor program “The Daily Show” launched the action-packed adventures of “The Decider,” featuring Bush as a comic book hero. In Washington City, the corridors of power were menaced by crippling indecision until…The Decider. http://politicalhumor.about.com/od/dailyshow/v/thedecider.htm

3. Hansen, J. et. al. Earth’s Energy Imbalance: Confirmation and Implications. Science 3 June 2005: Vol. 308. no. 5727, pp. 1431–1435.

4. Hansen, J. et. al. Earth’s Energy Imbalance: Confirmation and Implications. Science 3 June 2005: Vol. 308. no. 5727, pp. 1431–1435.

5. In the United States, the largest methane emissions come from the decomposition of wastes in landfills, ruminant digestion and manure management associated with domestic livestock, natural gas and oil systems, and coal mining. Table 1 shows the level of emissions from individual sources for the years 1990 and 1997 to 2003.

Table 1
U.S. Methane Emissions by Source (TgCO₂ Equivalents)

Source category	1990	1997	1998	1999	2000	2001	2002	2003
Landfills	172.2	147.4	138.5	134.0	130.7	126.2	126.8	131.2
Natural Gas Systems	128.3	133.7	131.8	127.4	132.1	131.8	130.6	125.9
Enteric Fermentation	117.9	118.3	116.7	116.8	115.6	114.5	114.6	115.0
Coal Mining	81.9	62.6	62.8	58.9	56.2	55.6	52.4	43.8
Manure Management	31.2	36.4	38.8	38.8	38.1	38.9	39.3	39.1
Wastewater Treatment	24.8	31.7	32.6	33.6	34.3	34.7	35.8	36.8
Petroleum Systems	20.0	18.8	18.5	17.8	17.6	17.4	17.1	17.1
Rice Cultivation	7.1	7.5	7.9	8.3	7.5	7.6	6.8	6.9
Stationary Sources	7.8	7.4	6.9	7.1	7.3	6.7	6.4	6.7
Abandoned Coal Mines	6.1	8.1	7.2	7.3	7.7	6.9	6.4	6.4
Mobile Sources	4.8	4.0	3.9	3.6	3.4	3.1	2.9	2.7
Petrochemical Production	1.2	1.6	1.7	1.7	1.7	1.4	1.5	1.5
Iron and Steel	1.3	1.3	1.2	1.2	1.2	1.1	1.0	1.0
Agricultural Residue Burning	0.7	0.8	0.8	0.8	0.8	0.8	0.7	0.8
Total for U.S.	605.3	579.5	569.3	557.3	554.2	546.7	542.3	544.9

Source: US Emissions Inventory 2005: Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2003, http://www.epa.gov/methane/sources.html, accessed Feb. 14, 2007.

6. Ramanathan, V. & Carmichael, G. Global and regional climate changes due to black carbon. Geoscience March 23, 2008.

7. A very readable and accurate summary of methane sources and controls is “Methane May Pack Double the Climate Punch of Earlier Estimates,” Environmental News Service, http://www.ens-newswire.com/ens/jul2005/2005-07-19-01.asp.

8. Peter Brimblecombe, “The Big Smoke: A History of Air Pollution in London since Medieval Times,” Methuen, London (1987/88). One of the most entertaining and enlightening books ever written on the subject of air pollution. This is essential reading for a person in the field or aspiring to a career.

9. Mark Z. Jacobson, Atmospheric Pollution: history, science and regulation, Cambridge University Press, Cambridge, England (2002), p. 124.

10. Cooke, W.F.; Wilson, J.J.N. A global black carbon aerosol model. J of Geophys R. VOL. 101; ISSUE: D14 ; PBD: 27 Aug 1996.

A global inventory constructed for emissions of black carbon from fossil fuel combustion and biomass burning was implemented in a 3D global transport model and run for 31 model months, and results for January and July compared with measurements from the literature. The modeled values of black carbon mass concentration compared within a factor of 2 in continental regions and some remote regions but are higher than measured values in other remote marine regions and in the upper troposphere, explained by the coarse grid scale of the model, the simplicity of the current deposition scheme, and possibly too much black carbon being available for transport, which would also account for the disagreement in the upper troposphere. The disagreement may also be due to problems associated with the measurement of black carbon. Emissions from this database appear to provide a reasonable estimate of the annual emissions of black carbon to the atmosphere. Biomass burning emissions amount to 5.98 Tg and that from fossil fuel to 7.96 Tg. A local sensitivity analysis showed that black carbon has a lifetime between 6 and 10 days, depending on the transformation rate between hydrophobic and hydrophilic black carbon.

11. Forbes, M.S., Raison, R.J., Skjemstad, J.O. 2006. Formation, transformation and transport of black carbon (charcoal) in terrestrial and aquatic ecosystems. Science of the Total Environment 370, 190–206. Also, Preston, C.M., Schmidt, M.W.I. 2006. Black (pyrogenic) carbon: a synthesis of current knowledge and uncertainties with special consideration of boreal regions. Biogeoscience 3, 397–420.

12. Brodowski S., Amelung, W., Haumaier, L., Abetz, C., Zech, W. 2005. Morphological and chemical properties of black carbon in physical soil fractions as revealed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Geoderma 128, 116–129. Also, Forbes, M.S., Raison, R.J., Skjemstad, J.O. 2006. Formation, transformation and transport of black carbon (charcoal) in terrestrial and aquatic ecosystems. Science of the Total Environment 370, 190–206.

13. Bhugwant, C., et. al. Impact of traffic on black carbon aerosol concentration at la Réunion Island (Southern Indian Ocean). Atmospheric Environment Volume 34, Issue 20, 2000, Pages 3463–3473.

To gain information on particle pollution by mobile sources, 3 experiments were conducted during the 1996–1998 period at Saint-Denis, the biggest urban site of La Réunion island (21.5°S; 55.5°E), situated in the Indian Ocean. Black Carbon (BC) concentrations were recorded with an Aethalometer which show high levels whatever the season (daily average: 270–650 ng m-3). At this site, a marked diurnal BC concentration variation is also evidenced in accordance with the observed traffic pattern. Measured daytime BC concentrations are 2–4 times greater than nighttime values. Neither MBL height obtained by radio soundings nor wind speed or direction could explain satisfactorily the BC variations. A comparison with BC concentrations measured at other more remote sites of the island (Sainte-Rose and the altitude site Piton Textor) suggests that the background concentrations of the island are of the order 50 ngC m-3. These background values are almost never encountered in the main city (range: 80–2800 ngC m-3). We show that due to a singular convergence of parameters (topography of the island, road network, movement of population, quality of fuel), the city of Saint-Denis appears as polluted as continental European big cities.

14. Novakov T.; Bates T.S.; Quinn P.K. Shipboard measurements of concentrations and properties of carbonaceous aerosols during ACE-2. Tellus, Volume 52, Number 2, April 2000

Mass concentrations of total, organic and black carbon were derived by analyzing the supermicron and submicron aerosol fractions of shipboard collected samples in the eastern Atlantic Ocean as part of the second Aerosol Characterization Experiment (ACE-2). These analyses were complemented by experiments intended to estimate the water-soluble fraction of the submicron carbonaceous material. Results: Depending on the sample, between 35% and 80% of total aerosol carbon is associated with the submicron fraction. Total submicron carbon was well correlated with black carbon, a unique tracer for incomplete combustion. These correlations and the approximately constant total to black carbon ratios, suggest that the majority of submicron total carbon is of primary combustion derived origin. No systematic relationship between total submicron aerosol carbon and sulfate concentrations was found. Sulfate concentrations were, with a few exceptions, significantly higher than total carbon. Experiments demonstrated that water exposure removed between 36% and 72% of total carbon from the front filter, suggesting that a substantial fraction of the total submicron aerosol organic carbon is water-soluble. An unexpected result of this study is that water exposure of filter samples caused substantial removal of, nominally insoluble, submicron black carbon. Possible reasons for this observation are discussed.

15. [59]BERUBE, K.A., JONES, T.P., WILLIAMSON, B.J., WINTERS, C., MORGAN, A.J., & RICHARDS, R.J.Physicochemical characterisation of diesel exhaust particles: factors for assessing biological activity
Atmospheric Environment 33 (1999) 1599-1614

From Cardiff. Source was a 1985 Japanese ISEKI tractor burning Esso 2000 Diesel and a 20/30 mixture of Esso light engine oil. Operated at 2000 rpm. Details of methodology.

Define four basic shapes:
1.Spherulites (individual particles); 2. Chains or clusters of spherulites; 3. Spherules (large bodies of spherulites; 4. Flake-like bodies. Equivalent spherical diameter of spherulites was 0.23 microns; Distributions of particle size by number showed 10% were ultrafines; 89.5% were fine (0.1-2.0 microns) and 0.4% coarse (greater than 2.5 microns). But distribution by mass showed 0.01% ultrafine, 52.6% fine; and 47.4% coarse. Electron probe X-ray microanalysis showed presence of C,O,Na,Mg,K,Al,Si,P,S,Cl,and Ca along with a range of metals (Ti,Mn,Fe,Zn,&Cr). By analysis before and after sonication of particles in water, the mobile sorbed metals were Mg,P,Ca,Cr,Mn,Zn,Sr,Mo,Ba,Na,Fe,S, & Si. Stress differences between sonicated and impacted diesel particles–these differences are likely to affect toxicity. Excellent pictures. A definitive article.

16. Ch_lek, P. , et. al. Black carbon and absorption of solar radiation by clouds. Journal of Geophysical Research, Volume 101, Issue D18, p. 23365–23372

The exact solution of the scattered electromagnetic field from a water droplet containing an arbitrarily located spherical black carbon particle is used to investigate the effect of black carbon on the absorption of solar radiation by clouds. When droplet absorption is averaged over all possible locations of black carbon within a droplet, the averaged absorption is close to the value calculated using the effective medium approximation. The preferential black carbon location on the top or close to the bottom of the droplet leads to an increased absorption. The estimated upper bound on the increased absorption of solar radiation (global and annual average) is 1-3 W/m² over the absorption of pure water clouds.

17. Jacobson, M.Z., Effects of absorption by soot inclusions within clouds and precipitation on global climate, J. Phys. Chem., 110, 6860–6873, 2006.

18. Hansen, A.D.A. Aerosol Black Carbon Measurements at the South Pole: Initial Results, 1986–1987. Geophysical Research Letters, VOL. 15, NO. 11, PAGES 1193–1196, 1988.

In December 1986 an aethalometer was installed at the NOAA/GMCC South Pole Observatory to measure concentrations of the combustion effluent tracer species aerosol black carbon (BC) with a time resolution of one hour. Hourly data covering a 1-year period from December 1986 through November 1987 showed infrequent events in which the concentrations increased greatly for periods of a few hours. These were attributed to local contamination. The remaining background data then yielded daily average BC concentrations generally ranging from 50 ng/m³ to 5 ng m/3, with a minimum in the early austral winter. The results imply long-range transport and suggest a minimum value of the order of 10 pg m/3 for its global background concentration.

19. McConnell, J.R., et. al. 20^th-Century Industrial Black Carbon Emissions Altered Arctic Climate Forcing. 317 Science 5843, 7 Sep. 2007, pp. 1381–1384.

Black carbon (BC) from biomass and fossil fuel combustion alters chemical and physical properties of the atmosphere and snow albedo, yet little is known about its emission or deposition histories. Measurements of BC, vanillic acid, and non-sea-salt sulfur in ice cores indicate that sources and concentrations of BC in Greenland precipitation varied greatly since 1788 as a result of boreal forest fires and industrial activities. Beginning about 1850, industrial emissions resulted in a sevenfold increase in ice-core BC concentrations, with most change occurring in winter. BC concentrations after about 1951 were lower but increasing. At its maximum from 1906 to 1910, estimated surface climate forcing in early summer from BC in Arctic snow was about 3 watts per square meter, which is eight times the typical preindustrial forcing value.

20. Hansen, J. & Nazarenko, L. Soot Climate Forcing via Snow and Ice Albedos. PNAS.

Using the NASA GISS climate computer model to simulate effects of greenhouse gases and other factors on world climate and incorporating data from NASA spacecraft that monitor the Earth’s surface, vegetation, oceans and atmospheric qualities, the calculated global warming from soot in snow and ice, by itself in an 1880–2000 simulation, accounted for 25 percent of observed global warming. NASA’s Terra and Aqua satellites observe snow cover and reflectivity at multiple wavelengths, which allows quantitative monitoring of changing snow cover and effects of soot on snow. The researchers found that observed warming in the Northern Hemisphere was large in the winter and spring at middle and high latitudes. These observations were consistent with the researchers’ climate model simulations, which showed some of the largest warming effects occurred when there was heavy snow cover and sufficient sunlight.

21. Ramanathan, V. et. al. Atmospheric brown clouds: Hemispherical and regional variations in long-range transport, absorption, and radiative forcing. J. Geophys. Res., 112, D22S21, doi:10.1029/2006JD008124.

The study uses satellite observations, global assimilated aerosol data sets, Atmospheric Brown Clouds (ABC) observatories, a Monte Carlo aerosol-cloud-radiation model and a regional chemical transport model (STEM-2K) to characterize the spatial extent of brown clouds, regional and megacity ABC hot spots, chemical composition and the direct radiative forcing. It presents the first annual cycle of aerosol observations and forcing from the ABC observatories in the Indo-Asia-Pacific regions. East Asia, Indo-Gangetic Plains, Indonesian region, southern Africa and the Amazon basin are the regional hot spots defined by the criteria that anthropogenic aerosol optical depths (AODs) should exceed 0.3 and absorbing AOD > 0.03. Over these hot spots, as well as in other polluted oceanic regions, the EC mass exceeds 0.5 ?g m-3, the OC mass exceeds 2 ?g m-3 and sulfate mass exceeds 10 ?g m-3 from the surface to 3 km. The brown clouds also have strong seasonal dependence. In the tropics the seasonal dependence is driven by pollution accumulating during the dry seasons, December to February in Northern Hemisphere tropics and June to August in Southern Hemisphere tropics. In the extratropics the pollution peaks during the summer. The brown cloud problem is not restricted to the tropical regions. Over the eastern half of US and western Europe the AODs exceeds 0.2 and absorption AODs exceed 0.02. Brown clouds also extend well into the western Pacific Ocean, the Indian Ocean reaching as far south as 60°S and the eastern Atlantic Ocean. The largest total SO₂ emission occurs over China and US, while SO₂ emission per unit surface area is maximum over Germany and England. The largest total EC and OC emissions occur over China, but the largest OC emission per unit surface area occur over India. As a result, the maximum negative annual mean TOA direct forcing is over India and Germany. The surface annual-diurnal mean dimming over the regional hot spots is of the order of-10 W m-2 and-20 W m-2 over megacity hotpots.

22. Menon, S., et. al. Climate Effects of Black Carbon Aerosols in China and India. 297 Science 5590, pp. 2250–2253, 27 September 2002, DOI: 10.1126/science.1075159.

In recent decades, there has been a tendency toward increased summer floods in south China, increased drought in north China, and moderate cooling in China and India while most of the world has been warming. Using a global climate model to investigate possible aerosol contributions to these trends, researchers found precipitation and temperature changes in the model that comparable to those observed if the aerosols included a large proportion of absorbing black carbon (“soot”), similar to observed amounts. Absorbing aerosols heat the air, alter regional atmospheric stability and vertical motions, and affect the large-scale circulation and hydrologic cycle with significant regional climate effects.

23. Andreae, M.O., Gelencsér, A. 2006. Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols. Atmospheric Chemistry and Physics 6, 3131–3148.

Although the definition and measurement techniques for atmospheric “black carbon” (“BC”) or “elemental carbon” (“EC”) have long been subjects of scientific controversy, the recent discovery of light-absorbing carbon that is not black (“brown carbon, or C brown”) makes it imperative to reassess and redefine the components that make up light-absorbing carbonaceous matter (LAC) in the atmosphere. Evidence for the atmospheric presence of C brown comes from (1) spectral aerosol light absorption measurements near specific combustion sources, (2) observations of spectral properties of water extracts of continental aerosol, (3) laboratory studies indicating the formation of light-absorbing organic matter in the atmosphere, and (4) indirectly from the chemical analogy of aerosol species to colored natural humic substances. We show that brown carbon may severely bias measurements of “BC” and “EC” over vast parts of the troposphere, especially those strongly polluted by biomass burning, where the mass concentration of C brown is high relative to that of soot carbon. Chemical measurements to determine“EC” are biased by the refractory nature of C brown as well as by complex matrix interferences. Optical measurements of “BC” suffer from a number of problems: (1) many of the presently used instruments introduce a substantial bias into the determination of aerosol light absorption, (2) there is no unique conversion factor between light absorption and “EC”or “BC” concentration in ambient aerosols, and (3) the difference in spectral properties between the different types of LAC, as well as the chemical complexity of C brown, lead to several conceptual as well as practical complications. We also suggest that due to the sharply increasing absorption of C brown towards the UV, single-wavelength light absorption measurements may not be adequate for the assessment of absorption of solar radiation in the troposphere. We discuss the possible consequences of these effects for our understanding of tropospheric processes, including their influence on UV-irradiance, atmospheric photochemistry and radiative transfer in clouds.

24. Andreae, M.O., Gelencsér, A. 2006. Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols. Atmospheric Chemistry and Physics 6, 3131–3148.

Although the definition and measurement techniques for atmospheric “black carbon” (“BC”) or “elemental carbon” (“EC”) have long been subjects of scientific controversy, the recent discovery of light-absorbing carbon that is not black (“brown carbon, or C brown”) makes it imperative to reassess and redefine the components that make up light-absorbing carbonaceous matter (LAC) in the atmosphere. Evidence for the atmospheric presence of C brown comes from (1) spectral aerosol light absorption measurements near specific combustion sources, (2) observations of spectral properties of water extracts of continental aerosol, (3) laboratory studies indicating the formation of light-absorbing organic matter in the atmosphere, and (4) indirectly from the chemical analogy of aerosol species to colored natural humic substances. We show that brown carbon may severely bias measurements of “BC” and “EC” over vast parts of the troposphere, especially those strongly polluted by biomass burning, where the mass concentration of C brown is high relative to that of soot carbon. Chemical measurements to determine“EC” are biased by the refractory nature of C brown as well as by complex matrix interferences. Optical measurements of “BC” suffer from a number of problems: (1) many of the presently used instruments introduce a substantial bias into the determination of aerosol light absorption, (2) there is no unique conversion factor between light absorption and “EC”or “BC” concentration in ambient aerosols, and (3) the difference in spectral properties between the different types of LAC, as well as the chemical complexity of C brown, lead to several conceptual as well as practical complications. We also suggest that due to the sharply increasing absorption of C brown towards the UV, single-wavelength light absorption measurements may not be adequate for the assessment of absorption of solar radiation in the troposphere. We discuss the possible consequences of these effects for our understanding of tropospheric processes, including their influence on UV-irradiance, atmospheric photochemistry and radiative transfer in clouds.

25. The Intergovernmental Panel on Climate Change (IPCC) was jointly established by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) in 1988. Its terms of reference include (i) to assess available scientific and socio-economic information on climate change and its impacts and on the options for mitigating climate change and adapting to it and (ii) to provide, on request, scientific/technical/socio-economic advice to the Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change (UNFCCC). From 1990, the IPCC has produced a series of Assessment Reports, Special Reports, Technical Papers, methodologies and other products that have become standard works of reference, widely used by policymakers, scientists and other experts.

26. p. 2-5 and p. 2-33.

27. Sato M., Hansen J.,, et. al. Global atmospheric black carbon inferred from AERONET. Proceedings of the National Academy of Sciences Applied Biological Sciences, May 13, 2003.

AERONET, a network of well calibrated sunphotometers, provides data on aerosol optical depth and absorption optical depth at >250 sites around the world. The spectral range of AERONET allows discrimination between constituents that absorb most strongly in the UV region, such as soil dust and organic carbon, and the more ubiquitously absorbing black carbon (BC). AERONET locations, primarily continental, are not representative of the global mean, but they can be used to calibrate global aerosol climatologies produced by tracer transport models. We find that the amount of BC in current climatologies must be increased by a factor of 2–4 to yield best agreement with AERONET, in the approximation in which BC is externally mixed with other aerosols. The inferred climate forcing by BC, regardless of whether it is internally or externally mixed, is ~1 W/m² , most of which is probably anthropogenic. This positive forcing (warming) by BC must substantially counterbalance cooling by anthropogenic reflective aerosols. Thus, especially if reflective aerosols such as sulfates are reduced, it is important to reduce BC to minimize global warming.

28. Jacobson, M Z. Attribution of Regional and Global Climate Change: Relative Effects of Fossil-Fuel Soot, Methane, Other Greenhouse Gases and Particles, and Urbanization.

Black carbon, the main component of fossil-fuel soot (FFS), warms the air first by absorbing sunlight. Its absorption is enhanced by optical focusing when it becomes coated during vapor condensation or aerosol-aerosol coagulation, when it enters cloud drops or ice crystals during nucleation scavenging or aerosol-hydrometeor coagulation, and when it is surrounded by sea ice or snow following its precipitation or dry deposition. Its absorption over snow, sea ice, desert, fog, and cloud surfaces is further enhanced by the high reflectivity of these surfaces, which increases the number of photons hitting a soot particle. Although soot has a short lifetime, the air that it warms persists to larger scales. Soot’s effective lifetime is also extended when it deposits to snow and sea ice. Since the organic material emitted with FFS is mostly hydrophobic, soot’s effects on cloud activation are delayed thus weaker than sulfate’s effects. Here new results for the climate response of fossil-fuel soot (black carbon, organic matter, sulfate), accounting for the factors listed above and for size resolution of aerosol particles and clouds and the aging of soot through the treatment of two size distributions, are presented. The results are compared with the climate responses of all anthropogenic aerosol particles, anthropogenic methane, all anthropogenic greenhouse gases, all anthropogenic greenhouse gases and aerosol particles, and urbanization. Fossil-fuel sources of black carbon treated include land-based, shipping, and aircraft. The study finds that fossil-fuel soot appears to have a stronger effect on global near-surface temperatures than either methane or urbanization, thus it may be the second-leading cause of historic near-surface global warming after carbon dioxide. Methane is found to have a stronger effect on near-surface temperatures than urbanization. FFS exacerbates warming due to greenhouse gases in Russia and over the Arctic sea ice. FFS causes little regional cooling in contrast to all aerosol particles, which, on their own, cause strong cooling in the southeast U.S., Europe, and China. The combination of all anthropogenic aerosol particles and greenhouse gases explains much of the difference between current and historic regional temperatures on a global scale. Whereas methane and other greenhouse gases cool the stratosphere, neither FFS nor urbanization do so significantly. The results here apply only to fossil-fuel soot. Biomass-burning particles, which contain black carbon, have a different composition from FFS and a different climate effect.

Also, Amanda Leigh Haag, “The even darker side of brown clouds,” Nature Reports Climate Change doi:10.1038/climate.2007.41.

29. Jacobson, M.Z. Strong radiative heating due to the mixing state of black carbon in atmospheric aerosols. 409 Nature 6821, pp. 695–697 (2001).

Aerosols affect the Earth’s temperature and climate by altering the radiative properties of the atmosphere. A large positive component of this radiative forcing from aerosols is due to black carbon-soot that is released from the burning of fossil fuel and biomass, and, to a lesser extent, natural fires, but the exact forcing is affected by how black carbon is mixed with other aerosol constituents. From studies of aerosol radiative forcing, it is known that black carbon can exist in one of several possible mixing states; distinct from other aerosol particles (externally mixed) or incorporated within them (internally mixed), or a black-carbon core could be surrounded by a well mixed shell. It had been previously assumed that aerosols existed predominantly as an external mixture. However, simulating the evolution of the chemical composition of aerosols shows that the mixing state and direct forcing of the black-carbon component approach those of an internal mixture, largely due to coagulation and growth of aerosol particles. This, in turn, implies a higher positive forcing from black carbon than previously thought, suggesting that the warming effect from black carbon may nearly balance the net cooling effect of other anthropogenic aerosol constituents. The magnitude of the direct radiative forcing from black carbon itself exceeds that due to CH₄, suggesting that black carbon may be the second most important component of global warming after CO₂ in terms of direct forcing.

30. Jacobson, Mark Z. Strong radiative heating due to the mixing state of black carbon in atmospheric aerosols. Nature, v. 409, Issue 6821, pp. 695–697 (2001).

31. Andreae, M.O., Gelencsér, A. 2006. Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols. Atmospheric Chemistry and Physics 6, 3131–3148.

Although the definition and measurement techniques for atmospheric “black carbon” (“BC”) or “elemental carbon” (“EC”) have long been subjects of scientific controversy, the recent discovery of light-absorbing carbon that is not black (“brown carbon, or C brown”) makes it imperative to reassess and redefine the components that make up light-absorbing carbonaceous matter (LAC) in the atmosphere. Evidence for the atmospheric presence of C brown comes from (1) spectral aerosol light absorption measurements near specific combustion sources, (2) observations of spectral properties of water extracts of continental aerosol, (3) laboratory studies indicating the formation of light-absorbing organic matter in the atmosphere, and (4) indirectly from the chemical analogy of aerosol species to colored natural humic substances. We show that brown carbon may severely bias measurements of “BC” and “EC” over vast parts of the troposphere, especially those strongly polluted by biomass burning, where the mass concentration of C brown is high relative to that of soot carbon. Chemical measurements to determine“EC” are biased by the refractory nature of C brown as well as by complex matrix interferences. Optical measurements of “BC” suffer from a number of problems: (1) many of the presently used instruments introduce a substantial bias into the determination of aerosol light absorption, (2) there is no unique conversion factor between light absorption and “EC”or “BC” concentration in ambient aerosols, and (3) the difference in spectral properties between the different types of LAC, as well as the chemical complexity of C brown, lead to several conceptual as well as practical complications. We also suggest that due to the sharply increasing absorption of C brown towards the UV, single-wavelength light absorption measurements may not be adequate for the assessment of absorption of solar radiation in the troposphere. We discuss the possible consequences of these effects for our understanding of tropospheric processes, including their influence on UV-irradiance, atmospheric photochemistry and radiative transfer in clouds.

32. “Giant Atmospheric Brown Cloud Has Intercontinental Reach,” ScienceDaily, Dec. 17, 2004. The south Asian brown haze covers most of the Arabian Sea, Bay of Bengal and the south Asian region. It occurs every year, and extends from about November to April and possibly longer. The black carbon and other species in the haze reduce the average radiative heating of the ocean by as much as 10 percent and enhance the atmospheric solar radiative heating by 50 to 100 percent. V. Ramanathan, V., Crutzen, P. J., Mitra, A. P. and Sikka, D. The Indian Ocean Experiment and the Asian Brown Cloud.

33. Veerabhadran Ramanathan, V., Ramana1, M.V., Roberts, G., et. al. Warming trends in Asia amplified by brown cloud solar absorption. Nature 448, 575–578 (2 August 2007).

Atmospheric brown clouds are mostly the result of biomass burning and fossil fuel consumption. They consist of a mixture of light-absorbing and light-scattering aerosols and therefore contribute to atmospheric solar heating and surface cooling. The sum of the two climate forcing terms—the net aerosol forcing effect—is thought to be negative and may have masked as much as half of the global warming attributed to the recent rapid rise in greenhouse gases. There is, however, at least a fourfold uncertainty in the aerosol forcing effect. Atmospheric solar heating is a significant source of the uncertainty, because current estimates are largely derived from model studies. Here we use three lightweight unmanned aerial vehicles that were vertically stacked between 0.5 and 3 km over the polluted Indian Ocean. These unmanned aerial vehicles deployed miniaturized instruments measuring aerosol concentrations, soot amount and solar fluxes. During 18 flight missions the three unmanned aerial vehicles were flown with a horizontal separation of tens of metres or less and a temporal separation of less than ten seconds, which made it possible to measure the atmospheric solar heating rates directly. We found that atmospheric brown clouds enhanced lower atmospheric solar heating by about 50 percent. Our general circulation model simulations, which take into account the recently observed widespread occurrence of vertically extended atmospheric brown clouds over the Indian Ocean and Asia, suggest that atmospheric brown clouds contribute as much as the recent increase in anthropogenic greenhouse gases to regional lower atmospheric warming trends. We propose that the combined warming trend of 0.25 K per decade may be sufficient to account for the observed retreat of the Himalayan glaciers.

34. Jacobsen, M.Z. The climate response of fossil-fuel and biofuel soot, accounting for soot’s feedback to snow and sea ice albedo and emissivity, J. Geophys. Res. 109,D21201, doi:10.1029/2004JD004945, 2004.

35. Black Soot and Snow: A Warmer Combination

Hansen and Nazarenko used a leading worldwide-climate computer model to simulate effects of greenhouse gases and other factors on world climate. The model incorporated data from NASA spacecraft that monitor the Earth’s surface, vegetation, oceans and atmospheric qualities. The calculated global warming from soot in snow and ice, by itself in an 1880–2000 simulation, accounted for 25 percent of observed global warming. NASA’s Terra and Aqua satellites are observing snow cover and reflectivity at multiple wavelengths, which allows quantitative monitoring of changing snow cover and effects of soot on snow.

The researchers found that observed warming in the Northern Hemisphere was large in the winter and spring at middle and high latitudes. These observations were consistent with the researchers’ climate model simulations, which showed some of the largest warming effects occurred when there was heavy snow cover and sufficient sunlight.

36. Flanner, M.G. et. Al. Present-day climate forcing and response from black carbon in snow. J. Geophys. Res., 112, D11202, doi:10.1029/2006JD008003.

To improve understanding of climate forcing and response from black carbon (BC) in snow, the Snow, Ice, and Aerosol Radiative (SNICAR) model was applied, coupled to a general circulation model with prognostic carbon aerosol transport. Interannual varying biomass burning BC emissions, snow aging, and aerosol scavenging by snow meltwater were accounted for. The rate of snow aging determines snowpack effective radius (r e), which directly controls snow reflectance and the magnitude of albedo change caused by BC. For a reasonable r e range, reflectance reduction from BC varies threefold. Inefficient meltwater scavenging keeps hydrophobic impurities near the surface during melt and enhances forcing. Applying biomass burning BC emission inventories for a strong (1998) and weak (2001) boreal fire year, global annual mean BC/snow surface radiative forcing from all sources (fossil fuel, biofuel, and bio-mass burning) were estimated at +0.054 (0.007–0.13) and +0.049 (0.007–0.12) W m-2, respectively. Snow forcing from only fossil fuel + biofuel sources is +0.043 W m-2 (forcing from only fossil fuels is +0.033 W m-2), suggesting that the anthropogenic contribution to total forcing is at least 80%. The 1998 global land and sea-ice snowpack absorbed 0.60 and 0.23 W m-2, respectively, because of direct BC/snow forcing. The forcing is maximum coincidentally with snowmelt onset, triggering strong snow-albedo feedback in local springtime. Consequently, the “efficacy” of BC/snow forcing is more than three times greater than forcing by CO₂. The 1998 and 2001 land snowmelt rates north of 50°N are 28% and 19% greater in the month preceding maximum melt of control simulations without BC in snow. With climate feedbacks, global annual mean 2-meter air temperature warms 0.15 and 0.10°C, when BC is included in snow, whereas annual arctic warming is 1.61 and 0.50°C. Stronger high-latitude climate response in 1998 than 2001 is at least partially caused by boreal fires, which account for nearly all of the 35% biomass burning contribution to 1998 arctic forcing. Efficacy was anomalously large in this experiment, however, and more research is required to elucidate the role of boreal fires, which we suggest have maximum arctic BC/snow forcing potential during April–June. Model BC concentrations in snow agree reasonably well (r = 0.78) with a set of 23 observations from various locations, spanning nearly 4 orders of magnitude. We predict concentrations in excess of 1000 ng g-1 for snow in northeast China, enough to lower snow albedo by more than 0.13. The greatest instantaneous forcing is over the Tibetan Plateau, exceeding 20 W m-2 in some places during spring. These results indicate that snow darkening is an important component of carbon aerosol climate forcing.

Research from ancient sediment cores indicates that a warming climate could make the world’s arctic tundra far more susceptible to fires than previously thought. The findings are important given the potential for tundra fires to release organic carbon—which could add significantly to the amount of greenhouse gases already blamed for global warming.
http://www.sciencedaily.com/releases/2008/03/080304200902.htm

37. Bond, T. C. et. al. A technology-based global inventory of black and organic carbon emissions from combustion, J. Geophys. Res., 109 (D14203),(2004). doi:10.1029/2003JD003,697.

38. Koch, D. & Hansen J. Distant origins of Arctic black carbon: A Goddard Institute for Space Studies Model E experiment, J. Geophys. Res.,110(D04204), (2005), doi:10.1029/2004JD005,296.

39. McConnell, J. R., et al. 20^th-century industrial black carbon emissions altered arctic climate forcing, Science, 317(5843) (2007) 1381-1384, doi:10.1126/science.1144,856.

40. Quinn, P. K., et al. (2007), Short-lived pollutants in the Arctic: Their climate impact and possible mitigation strategies, Submitted to Atmos. Chem. Phys.

41. Streets, D.G. et. al. Black carbon emissions in China. 35 Atmospheric Environment 25, Sep. 2001, pp. 4281–4296
Black carbon (BC) is an important aerosol species because of its global and regional influence on radiative forcing and its local effects on the environment and human health. We have estimated the emissions of BC in China, where roughly one-fourth of global anthropogenic emissions is believed to originate. China’s high rates of usage of coal and biofuels are primarily responsible for high BC emissions. This paper pays particular attention to the application of appropriate emission factors for China and the attenuation of these emissions where control devices are used. Nevertheless, because of the high degree of uncertainty associated with BC emission factors, we provide ranges of uncertainty for our emission estimates, which are approximately a factor of eight. In our central case, we calculate that BC emissions in China in 1995 were 1342 Gg, about 83% being generated by the residential combustion of coal and biofuels. We estimate that BC emissions could fall to 1224 Gg by 2020. This 9% decrease in BC emissions can be contrasted with the expected increase of 50% in energy use; the reduction will be obtained because of a transition to more advanced technology, including greater use of coal briquettes in place of raw coal in cities and towns. The increased use of diesel vehicles in the future will result in a greater share of the transport sector in total BC emissions. Spatially, BC emissions are predominantly distributed in an east–west swath across China’s heartland, where the rural use of coal and biofuels for cooking and heating is widespread. This is in contrast to the emissions of most other anthropogenically derived air pollutants, which are closely tied to population and industrial centers.

42. [10] NEAS, L.M., SCHWARTZ, J., & DOCKERY, D.
A case-crossover analysis of air pollution and mortality in Philadelphia
Environmental Health Perspectives 107; 629–631; 1999

Reanalysis to counter criticism that previous data analysis by these authors did not sufficiently control for season and day of the week. Data from 1973–1980. Present finding with a case-crossover design is that 100 microgram/m³ increase in TSP is associated with increase in all cause mortality (OR of 1.056). For those over 65 years, OR was 1.074; and for cardiovascular disease was 1.063.

Data analysis confirms previous conclusions from time-series data.

[11]
SAMET, J.M., ZEGER, S.L., DOMINICI, F., CURRIERO, F., COURSAC, I., DOCKERY, D.W., SCHWARTZ, J., & ZANOBETTI, A.
The National morbidity, mortality, and air pollution study: Part II
Morbidity and mortality from air pollution in the United States
Health Effects Institute; Research Report: Number 94, Part II; June 2000; pp 82.

90 cities in different regions of the US, covering all areas. Daily PM₁₀ values given for 1987 to 1994. Also O₃, SO₂, NO₂ and CO. Univariate analysis showed highest values for SO₂, with CO second, NO₂ third, and PM₁₀ fourth. Distributed lag models give higher values, and authors note that the effects of pollution do not reach 0 until a lag of 5 days has occurred. Authors conclude: “Overall, this study provides strong evidence of association between PM₁₀ levels and exacerbation of chronic heart and lung disease sufficiently severe to warrant hospitalization.” Effect of PM₁₀ on mortality generally higher in Northeast, industrial Midwest, and southern California than in other regions.

[1390] JERRETT, M., & FINKELSTEIN, M.
Geographies of risk in studies linking chronic air pollution exposure to health outcomes
J Toxicology & Environmental Health, Part A; 68; 1207–1242, 2005

A remarkable article that is difficult to summarize. It integrates new approaches to calculating individual and population exposures on the basis of using the nearest monitor coupled with the data on location from GPS information and time activity diaries. Extends this by also using individual data on occupational and socioeconomic factors and comments on relevance of this information to longitudinal studies. “A key premise is that researchers should target studies with high degrees of overlap between geographies of exposure and susceptibility.”

43. Glaser, B., et. al. Source Apportionment of Organic Pollutants of a Highway-Traffic-Influenced Urban Area in Bayreuth (Germany) Using Biomarker and Stable Carbon Isotope Signatures. Environ. Sci. Technol., 39 (11), 3911–3917, 2005. 10.1021/es050002p.

Traffic-and urban-influenced areas are prone to enhanced pollution with products of incomplete combustion of fossil fuels and bio-mass such as black carbon or polycyclic aromatic hydrocarbons (PAHs). Black carbon is composed of aromatic and graphitic structures and may act as a carrier for pollutants such as PAHs and heavy metals. However, little is known about possible contributions of traffic-derived black carbon to the black carbon inventory in soils. Similar uncertainties exist regarding the contribution of different pollutant sources to total PAH and black carbon contents. Therefore, the objective of this study was to quantify the importance of traffic pollution to black carbon and PAH inventories in soils. PAH contamination of soils adjacent to a major German highway in the urban area of Bayreuth with about 50,000 vehicles per day was in the same order of magnitude compared to highway-close soils reported in other studies. Using molecular (black carbon and PAHs) and compound-specific stable carbon isotope evidence (PAHs) it was demonstrated that this contamination originated not only from automobile exhausts, here primarily diesel, but also from tire abrasion and tailpipe soot which significantly contributed to the traffic-caused black carbon and PAH contamination. Low molecular weight PAHs were more widely transported than their heavy molecular counterparts (local distillation), whereas highway-traffic-caused black carbon contamination was distributed to at least 30 m from the highway.

44. In a carcinogenicity study, study groups of rats were treated with multiple dust instillations, i.e. 30 instillations of 0.5 mg amorphous SiO_2 at intervals of 2 weeks, 10 instillations of 0.5 mg of ultrafine carbon black or 1 mg coal at weekly intervals.
The analyses of the bronchoalveolar lavage fluid (BALF) 9 months after start of the lifetime study found a 2.5-to 7.7-fold increase for lactate dehydrogenase (LDH), total protein, alkaline phosphatase and glutamyl transferase (GT) compared to the control. Cell counts in the BALF were quartz without PVNO (leukocytes: 480.000, PMN: 190.000), quartz with PVNO (leukocytes: 300.000, PMN: 100.000), amorphous SiO_2 (leukocytes: 570.000, PMN: 315.000), carbon black (leukocytes: 390.000, PMN: 150.000) and coal (leukocytes: 200.000, PMN: 65.000).

45. Nemmar A, Hoet PH, Vanquickenborne B, Dinsdale D, Thomeer M, Hoylaerts MF, Vanbilloen H, Mortelmans L, Nemery B.
Five healthy volunteers, “Technegas,” an aerosol consisting mainly of ultrafine (99m) Technetium-labeled carbon particles (<100 nm). The distribution of radioactivity after the inhalation of already after 1 minute radioactivity was detected in blood, reaching a maximum between 10 and 20 minutes, and remaining at this level up to 60 minutes. Thin layer chromatography of blood showed that in addition to a species corresponding to oxidized (99m)Tc, ie, pertechnetate, there was also a species corresponding to particle-bound (99m)Tc. Gamma camera images showed substantial radioactivity over the liver and other areas of the body. A similar study by others failed to replicate these results however. See Mills NL, Amin N, Robinson SD, Anand A, Davies J, Patel D, de la Fuente JM, Cassee FR, Boon NA, MacNee W, Millar AM, Donaldson K, Newby DE. Do inhaled carbon nanoparticles translocate directly into the circulation in humans? Am J Respir Crit Care Med. 173:426–431. doi: 10.1164/rccm.200506-865OC. 15-2-2006

46. GAUDERMAN, W.J., AVOL, E., GILLILAND, F., VORA, H., THOMAS, D., BERHANE, K., McCONNELL, R., KUENZLI, N., LURMANN, F., RAPPAPORT, E., MARGOLIS, H., BATES, D., & PETERS, J.The Effect of air pollution on lung development from 10 to 18 years of ageNew Engl. J. Med 351; 1057–1067, 20041759 children of average age 10 years followed for 8 years with annual review and PF testing. Rate of attrition was 10% per year. Recruited from 12 Southern California Communities. Community levels of pollutants show O₃ varying from 28 to 66 ppb from 10 am to 6 pm; PM₁₀ from 15 to 69 micrograms/m³; NO₂ from 4 to 40 ppb; PM_2.5 from 5 to 29 micrograms/m³; Acid Vapor in ppb from 2 to 12 ppb; and elemental carbon from 0.1 to 1.3 micrograms/m³.In both girls and boys, all pollutants except ozone were associated with slower rates of growth of FEV₁ – for example for NO₂ over the range between communities, the growth of FEV₁ fell from about 1390 to 1290 in girls and from 2425 to 2330 in boys. Exclusion of highest and lowest points did not affect the regression relationship. Highest deficits recorded in relation to acid vapor exposure. Difference in MMEF generally larger than for other parameters, with the highest deficit of – 211 ml/sec recorded for NO₂. Table presents analysis of results from the main model, and for different models. These show same results for nonasthmatics; and no effects from gas stove use, maternal smoking in utero, pets at home, parental level of education, or short term effects of pollutants. A pioneer study.

47. S. Franco Suglia1, S.F. et. al. Association of Black Carbon with Cognition among Children in a Prospective Birth Cohort Study. Am J Epidemiol. 2008 Feb 1;167(3):280–6.

To assess relationship between black carbon and cognition, 202 Boston, Massachusetts, children (mean age = 9.7 years (standard deviation, 1.7) were enrolled in a prospective birth cohort study (1986–2001). Local black carbon levels were estimated using a validated spatiotemporal land-use regression model (mean predicted annual black carbon level, 0.56 mug/m(3) (standard deviation, 0.13). The Wide Range Assessment of Memory and Learning and the Kaufman Brief Intelligence Test were administered for assessment of cognitive constructs. In analysis adjusting for sociodemographic factors, birth weight, blood lead level, and tobacco smoke exposure, black carbon (per interquartile-range increase) was associated with decreases in the vocabulary (-2.2, 95% confidence interval (CI):-5.5, 1.1), matrices (-4.0, 95% CI:-7.6,-0.5), and composite intelligence quotient (-3.4, 95% CI:-6.6,-0.3) scores of the Kaufman Brief Intelligence Test and with decreases on the visual subscale (-5.4, 95% CI:-8.9,-1.9) and general index (-3.9, 95% CI:-7.5,-0.3) of the Wide Range Assessment of Memory and Learning. Higher levels of black carbon predicted decreased cognitive function across assessments of verbal and nonverbal intelligence and memory constructs.

48. KIM, J.J., SMORODINSKY, S., LIPSETT, M., SINGER, B.C., HODGSON, A.T., & OSTRO, B.Traffic-related air pollution near busy roads
Am J Respir Crit Care Med 170; 520–526; 2004

School-based cross sectional study conducted in Alameda County, in California which includes Oakland and about 20 kilometers south of it. Children in grades 3–5 enrolled, and 1,109 questionnaires were completed. 30% of households had incomes below the poverty line. Respiratory symptoms were associated with proximity to heavily traveled roads, and among those at their current residences for at least a year, the adjusted odds ratio for asthma in relationship to the interquartile difference in NO₂, was 1.07. The association with black carbon was also significant. Bronchitis prevalence rates were also associated with higher levels of both pollutants. Of the schools, lowest NO₂ was 19 ppb, and highest was 31 ppb.

49. [1340]MARSHALL, J.D., & BEHRENTZ, E.Vehicle self-pollution intake fraction: children’s exposure to school bus emissions
Environ Sci Technol 2005: 39; 2559-2563

Data from South Coast Air Basin of California using tracer gas (SF₆) to estimate children’s exposures. Six buses studied during nine runs with windows open and seven runs with closed windows. Results show high exposures of children to the school bus emissions, with exposures many times greater for the students on a particular bus than for the population at large.

50. Association of air pollution with increased incidence of ventricular tachyarrhythmias recorded by implanted cardioverter defibrillators
Environmental Health Perspectives, June, 2005 by Douglas W. Dockery, Heike Luttmann-Gibson, David Q. Rich, Mark S. Link, Murray A. Mittleman, Diane R. Gold, Petros Koutrakis, Joel D. Schwartz, Richard L. Verrier

Epidemiologic studies have demonstrated a consistent link between sudden cardiac deaths and particulate air pollution. We used implanted cardioverter defibrillator (ICD) records of ventricular tachyarrhythmias to assess the role of air pollution as a trigger of these potentially life-threatening events. The study cohort consisted of 203 cardiac patients with ICD devices in the Boston metropolitan area who were followed for an average of 3.1 years between 1995 and 2002. Fine particle mass and gaseous air pollution plus temperature and relative humidity were measured on almost all days, and black carbon, sulfate, and particle number on a subset of days. Date, time, and intracardiac electrograms of ICD-detected arrhythmias were downloaded at the patients’ regular follow-up visits (about every 3 months). Ventricular tachyarrhythmias were identified by electrophysiologist review. Risk of ventricular arrhythmias associated with air pollution was estimated with logistic regression, adjusting for season, temperature, relative humidity, day of the week, patient, and a recent prior arrhythmia. We found increased risks of ventricular arrhythmias associated with 2-day mean exposure for all air pollutants considered, although these associations were not statistically significant. We found statistically significant associations between air pollution and ventricular arrhythmias for episodes within 3 days of a previous arrhythmia. The associations of ventricular tachyar-rhythmias with fine particle mass, carbon monoxide, nitrogen dioxide, and black carbon suggest a link with motor vehicle pollutants. The associations with sulfate suggest a link with stationary fossil fuel combustion sources. Key words: air pollution, arrhythmias, epidemiology, fibrillation, heart arrest. Environ Health Perpect 113:670–674 (2005). doi:10.1289/ehp.7767 available via http://dx.doi.org/[Online 18 February 2005]

51. Peters, A., et. al. Air pollution and incidence of cardiac arrhythmia. Epidemiology. 2000 Jan;11 (1):11–7 10615837.

Air pollution episodes are associated with increased cardiovascular hospital admissions and mortality in time-series studies. Researchers tested the hypothesis that patients with implanted cardioverter defibrillators experience potentially life-threatening arrhythmias after such air pollution episodes. Comparing defibrillator discharge interventions among 100 patients with such devices in eastern Massachusetts, according to variations in concentrations of particulate matter, black carbon, and gaseous air pollutants that were measured daily for the years 1995 through 1997. A 26-ppb increase in nitrogen dioxide was associated with increased defibrillator interventions 2 days later (odds ratio = 1.8; 95% confidence interval = 1.1-2.9). Patients with ten or more interventions experienced increased arrhythmias in association with nitrogen dioxide, carbon monoxide, black carbon, and fine particle mass. These results suggest that elevated levels of air pollutants are associated with potentially life-threatening arrhythmia leading to therapeutic interventions by an implanted cardioverter defibrillator.

52. Gold, D.R., at. al. Air pollution and ST-segment depression in elderly subjects
Environmental Health Perspectives, July, 2005

Increased levels of daily ambient particle pollution have been associated with increased risk of cardiovascular morbidity. Black carbon (BC) is a measure of the traffic-related component of particles. Associations between ambient pollution and ST-segment levels in a repeated-measures study including 269 observations on 24 active Boston residents 61–88 years of age, each observed up to 12 times from June through September 1999. The protocol involved continuous Holter electrocardiogram monitoring including 5 minutes of rest, 5 minutes of standing, 5 minutes of exercise outdoors, 5 minutes of recovery, and 20 cycles of paced breathing. Pollution-associated ST-depression was estimated for a 10th-to 90th-percentile change in BC. The average ST-segment level, referenced to the P-R isoelectric values, for each portion of the protocol was calculated. The mean BC level in the previous 12 hours, and the BC level 5 hours before testing, predicted ST-segment depression in most portions of the protocol, but the effect was strongest in the postexercise periods. During postexercise rest, an elevated BC level was associated with -0.1 mm ST-segment depression (p = 0.02 for 12-hr mean BC; p = 0.001 for 5-hr BC) in continuous models. Elevated BC also predicted increased risk of ST-segment depression [greater than or equal to] 0.5 mm among those with at least one episode of that level of ST-segment depression. Carbon monoxide was not a confounder of this association. ST-segment depression, possibly representing myocardial ischemia or inflammation, is associated with increased exposure to particles, including black carbon, whose predominant source is traffic.

53. Jansen, K. L., et. al. Associations between health effects and particulate matter and black carbon in subjects with respiratory disease. Environ Health Perspect 113:1741–1746 (2005)

Measurements of fractional exhaled nitric oxide, spirometry, blood pressure, oxygen saturation of the blood, and pulse rate in 16 older subjects with asthma or chronic obstructive pulmonary disease (COPD) in Seattle, Washington. Data collected daily for 12 days. Simultaneously collected PM₁₀ and PM.2.5 filter samples at a central outdoor site, as well as outside and inside the subjects’ homes. Personal PM₁₀ filter samples were also collected. All filters were analyzed for mass and light absorbance. Analyzed within-subject associations between health outcomes and air pollution metrics using a linear mixed-effects model with random intercept, controlling for age, ambient relative humidity, and ambient temperature. For the 7 subjects with asthma, a 10 microg/cubic meter increase in 24-hr average outdoor PM₁₀ and PM_2.5 was associated with a 5.9 [95% confidence interval (CI), 2.9–8.9] and 4.2 ppb (95% CI, 1.3–7.1) increase in FE_NO, respectively. A 1 microg/cubic meter increase in outdoor, indoor, and personal black carbon (BC) was associated with increases in FE_NO of 2.3 ppb (95% CI, 1.1–3.6), 4.0 ppb (95% CI, 2.0–5.9), and 1.2 ppb (95% CI, 0.2–2.2), respectively. No significant association was found between PM or BC measures and changes in spirometry, blood pressure, pulse rate, or SaO₂.

54. Raitakari1,O.T. and Celermajer, D.S. Flow-mediated dilatation. Br J Clin Pharmacol. 2000 November; 50(5): 397–404.

Arterial endothelial dysfunction is one of the key early events in atherogenesis, preceding structural atherosclerotic changes. It is also important in the late stages of obstructive atherosclerosis, predisposing to constriction and/or thrombosis. Endothelial function can be measured in coronary arteries and in the periphery by measuring vasomotor function after intraarterial infusion of pharmacologic substances which enhance the release of endothelial nitric oxide. The disadvantage of these methods is their invasive nature, which generally makes them unsuitable for studies involving asymptomatic subjects. For this reason, noninvasive tests of endothelial function have been developed. In the most widely used of these, an ultrasound-based method, arterial diameter is measured in response to an increase in shear stress, which causes endothelium-dependent dilatation. Endothelial function assessed by this method correlates with invasive testing of coronary endothelial function, as well as with the severity and extent of coronary atherosclerosis. This noninvasive endothelial function testing has provided valuable insights into early atherogenesis, as well as into the potential reversibility of endothelial dysfunction by various strategies, including pharmacological agents (lipid lowering, ACE inhibition), l-arginine, antioxidants and hormones.

55. Adar,S.D., et. al. Ambient and Microenvironmental Particles and Exhaled Nitric Oxide Before and After a Group Bus Trip. Environ Health Perspect. 2007 April; 115(4): 507–512.

To examine associations between particle exposures and exhaled nitric oxide (FE_NO) 44 senior citizens, involving repeated trips aboard a diesel bus, samples of FE_NO collected before and after the trips were regressed against microenvironmental and ambient particle concentrations using mixed models controlling for subject, day, trip, vitamins, collection device, mold, pollen, room air nitric oxide, apparent temperature, and time to analysis. Although ambient concentrations were collected at a fixed location, continuous group-level personal samples characterized microenvironmental exposures throughout facility and trip periods. Two portable carts containing continuous air pollution monitors were used to measure group-level microenvironmental exposures to traffic-related pollutants, including fine particulate mass (< 2.5 microg/m aerodynamic diameter; PM_2.5), black carbon, and size-specific particle counts. Concentrations of PM_2.5, black carbon, fine particle counts, and coarse particle counts were systematically higher aboard the bus and during the trips than during periods spent at the living facilities. Black carbon, a common indicator for traffic, was most strongly enhanced by the bus trips, with a 9-fold increase in the mean concentration during bus periods. Concentrations of PM_2.5 and black carbon in ambient air were strongly correlated (r = 0.74). In pre-trip samples, both microenvironmental and ambient exposures to fine particles were positively associated with FE_NO. For example, an interquartile increase of 4 microg/m³ in the daily microenvironmental PM_2.5 concentration was associated with a 13% [95% confidence interval (CI), 2–24%) increase in FE_NO. After the trips, however, FE_NO concentrations were associated predominantly with microenvironmental exposures, with significant associations for concentrations measured throughout the whole day. Associations with exposures during the trip also were strong and statistically significant with a 24% (95% CI, 15–34%) increase in FE_NO predicted per interquartile increase of 9 microg/m³ in PM_2.5.

56. Hoek G, Brunekreef B, Goldbohm S, Fischer P, van den Brandt PA. Association between mortality and indicators of traffic-related air pollution in the Netherlands: a cohort study. Lancet 2002;360(9341):1203–9.

To assess the relation between traffic-related air pollution and mortality in participants of the Netherlands Cohort study on Diet and Cancer (NLCS), an ongoing study, a random sample of 5,000 was selected from the full cohort (age 55–69 years) from 1986 to 1994. Long-term exposure to traffic-related air pollutants (black smoke and nitrogen dioxide) was estimated for the 1986 home address. Exposure was characterized with the measured regional and urban background concentration and an indicator variable for living near major roads. The association between exposure to air pollution and (cause specific) mortality was assessed with Cox’s proportional hazards models, with adjustment for potential confounders. Of 4,492 participants, 489 (11%) with data died during the follow-up period. Cardiopulmonary mortality was associated with living near a major road (relative risk 1.95, 95% CI 1.09–3.52) and, less consistently, with the estimated ambient background concentration (1.34, 0.68–2.64). The relative risk for living near a major road was 1.41 (0.94–2.12) for total deaths. Non-cardiopulmonary, non-lung cancer deaths were unrelated to air pollution (1.03, 0.54–1.96 for living near a major road).

57. Peters A, von Klot S, Heier M, Trentinaglia I, Hörmann A, Wichmann H-E et al. (2004)
Exposure to Traffic and the Onset of Myocardial Infarction.
N Engl J Med; 351(17):1721–1730.

To assess whether the relationship between exposure to traffic-related air pollutants and onset of myocardial infarction 691 cases of myocardial infarction were identified using data from the Cooperative Health Research in the Region of Augsburg Myocardial Infarction Registry in Augsburg, in southern Germany, for February 1999 to July 2001, who had survived for at least 24 hours after the event, completed the registry’s standardized interview, and provided information on factors that may have triggered the myocardial infarction. Data on subjects’ activities during the four days preceding the onset of symptoms were collected with the use of patient diaries. An association was found between exposure to traffic and the onset of a myocardial infarction within one hour afterward (odds ratio, 2.92; 95 percent confidence interval, 2.22 to 3.83; P<0.001). The time the subjects spent in cars, on public transportation, or on motorcycles or bicycles was consistently linked with an increase in the risk of myocardial infarction. Adjusting for the level of exercise on a bicycle or for getting up in the morning changed the estimated effect of exposure to traffic only slightly (odds ratio for myocardial infarction, 2.73; 95 percent confidence interval, 2.06 to 3.61; P<0.001). The subject’s use of a car was the most common source of exposure to traffic; nevertheless, there was also an association between time spent on public transportation and the onset of a myocardial infarction one hour later, showing that transient exposure to traffic increases the risk of myocardial infarction in susceptible persons.

Peters A, Dockery DW, Muller JE, Mittleman MA (2001)
Increased particulate air pollution and the triggering of myocardial infarction.
Circulation. 2001 Jun 12;103(23):2810–5.

To assess whether increases in concentrations of ambient particles can trigger the onset of acute myocardial infarction (MI), 772 patients with MI in the greater Boston area between January 1995 and May 1996 were interviewed as part of the Determinants of Myocardial Infarction Onset Study. Hourly concentrations of particle mass <2.5 microm (PM_2.5), carbon black, and gaseous air pollutants were measured. A case-crossover approach was used to analyze the data for evidence of triggering. The risk of MI onset increased in association with elevated concentrations of fine particles in the previous 2-hour period. In addition, a delayed response associated with 24-hour average exposure 1 day before the onset of symptoms was observed. Multivariate analyses considering both time windows jointly revealed an estimated odds ratio of 1.48 associated with an increase of 25 microg/m(3) PM_2.5 during a 2-hour period before the onset and an odds ratio of 1.69 for an increase of 20 microg/m(3) PM_2.5 in the 24-hour period 1 day before the onset (95% CIs 1.09, 2.02 and 1.13, 2.34, respectively). The coarse fraction of PM₁₀, black carbon, and the gaseous air pollutants including carbon monoxide, NO₂, SO₂, and ozone showed positive associations, but none was statistically significant.

58. Peters A, von Klot S, Heier M, Trentinaglia I, Cyrys J, Hormann A, Hauptmann M, Wichmann HE, Lowel H. Particulate air pollution and nonfatal cardiac events.

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70. Pandey, M. R., Boleij, J. S., Smith, K. R. & Wafula, E. M. Lancet 1989; 1: 427-429.

71. Boy E., Bruce, N. & Delgado, H. Birth weight and exposure to kitchen wood smoke during pregnancy in rural Guatemala. Environ Health Perspect. 2002 Jan;110(1):109-14.

To assess whether domestic use of wood fuel is associated with reduced birth weight, independent of key maternal, social, and economic confounding factors, investigators studied 1,717 women and newborn children in rural and urban communities in rural Guatemala. They identified subjects through home births reported by traditional birth attendants in six rural districts (n = 572) and all public hospital births in Quetzaltenango city during the study period (n = 1,145). All were seen within 72 hr of delivery, and data were collected on the type of household fuel used, fire type, and socioeconomic and other confounding factors. Smoking among women in the study community was negligible. Children born to mothers habitually cooking on open fires (n = 861) had the lowest mean birth weight of 2,819 g [95% confidence interval (CI), 2,790-2,848]; those using a chimney stove (n = 490) had an intermediate mean of 2,863 g (95% CI, 2,824-2,902); and those using the cleanest fuels (electricity or gas, n = 365) had the highest mean of 2,948 g (95% CI, 2,898-2,998) (p< 0.0001). The percentage of low birth weights (< 500 g) in these three groups was 19.9% (open fire), 16.8% (chimney stove), and 16.0% (electricity/gas), (trend (p = 0.08). Confounding factors were strongly associated with fuel type, but after adjustment wood users still had a birth weight 63 g lower (p = 0.05; 95% CI, 0.4-126). This is the first report of an association between biofuel use and reduced birth weight in a human population. Although there is potential for residual confounding despite adjustment, the better-documented evidence on passive smoking and a feasible mechanism through carbon monoxide exposure suggest this association may be real. Because two-thirds of households in developing countries still rely on biofuels and women of childbearing age perform most cooking tasks, the attributable risk arising from this association, if confirmed, would be substantial.

72. Rinne, S.T.. et. al. Use of Biomass Fuel Is Associated with Infant Mortality and Child Health in Trend Analysis Am. J. Trop. Med. Hyg., 76(3), 2007, pp. 585-59.

Biomass fuel used for cooking results in widespread exposure to indoor air pollution (IAP), affecting nearly 3 billion people throughout the world. Few studies, however, have tested for an exposure–response relationship between biomass fuel and health outcomes. To assess the relationship between biomass fuel, infant mortality, and children’s respiratory symptoms. Eighty households in a rural community in Ecuador were selected based on their use of biomass fuel and questioned regarding a history of infant mortality and children’s respiratory symptoms. Carbon monoxide (CO) and particulate matter (PM) were measured in a subset of these homes to confirm the relationship between biomass fuel use and IAP. Results showed a significant trend for higher infant mortality among households that cooked with a greater proportion of biomass fuel (P = 0.008). Similar trends were noted for history of cough (P = 0.02) and earache (P < 0.001) among children living in these households.

73. Kumar, S. & Mehra, S. ARI And Indoor Air Pollution: Its Burden And Correlation. The Internet Journal of Pulmonary Medicine. 2007. Volume 8 Number 2. http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ijpm/vol8n2/ari.xml#r19

74. World Health Organization, Indoor air pollution in developing countries: a major environmental and public health challenge. Bulletin of the World Health Organization 2000.

75. Bruce N., Perez-Padilla R., & Albalak, R. Indoor air pollution in developing countries: a major environmental and public health challenge. Bull World Health Organ. 2000;78(9):1078-92.

Around 50% of people, almost all in developing countries, rely on coal and biomass in the form of wood, dung and crop residues for domestic energy. These materials are typically burnt in simple stoves with very incomplete combustion. Consequently, women and young children are exposed to high levels of indoor air pollution every day. There is consistent evidence that indoor air pollution increases the risk of chronic obstructive pulmonary disease and of acute respiratory infections in childhood, the most important cause of death among children under 5 years of age in developing countries. Evidence also exists of associations with low birth weight, increased infant and perinatal mortality, pulmonary tuberculosis, nasopharyngeal and laryngeal cancer, cataract, and, specifically in respect of the use of coal, with lung cancer. Conflicting evidence exists with regard to asthma. All studies are observational and very few have measured exposure directly, while a substantial proportion have not dealt with confounding. As a result, risk estimates are poorly quantified and may be biased. Exposure to indoor air pollution may be responsible for nearly 2 million excess deaths in developing countries and for some 4% of the global burden of disease. Indoor air pollution is a major global public health threat requiring greatly increased efforts in the areas of research and policy-making. Research on its health effects should be strengthened, particularly in relation to tuberculosis and acute lower respiratory infections. A more systematic approach to the development and evaluation of interventions is desirable, with clearer recognition of the interrelationships between poverty and dependence on polluting fuels.

76. U.S. Environmental Protection Agency (EPA) (2002) Health assessment document for diesel engine exhaust. Prepared by the National center for Environmental Assessment, Washington, D.C.

77. Mills, N.L. Ischemic and Thrombotic Effects of Dilute Diesel-Exhaust Inhalation in Men with Coronary Heart Disease. N Engl J Med 2007; 357:1075–1082.

Investigators recruited 20 men who had had a prior MI but were asymptomatic with no exertional angina and who were on optimal secondary-prevention medication. In the double-blind, randomized, crossover study—conducted at Umea University in Sweden—the men were exposed for one hour to either filtered air or dilute diesel-exhaust fumes (300 _g/m³) while intermittently riding a bicycle ergometer for two 15-minute periods, separated by 15-minute rest periods. Mills said the levels of diesel fumes in the study were chosen to mimic the sorts of air pollution that would be encountered in everyday life. During exposure, myocardial ischemia was quantified by ST-segment analysis using continuous 12-lead ECG. Six hours after exposure, vasomotor and fibrinolytic functions were assessed by means of intra-arterial agonist infusions. Heart rate increased similarly with exercise during both air and diesel exposures, but there was as much as a threefold increase in myocardial ischemia during exposure to diesel-exhaust fumes compared with filtered air (-22.4 vs-8 mV-sec; p<0.001). Exposure to diesel fumes did not aggravate preexisting vasomotor dysfunction, but it did dampen the acute release of endothelial tissue plasminogen activator by 35%.

78. Stefan Speidl, W. S. et. al. An increase of C-reactive protein is associated with enhanced activation of endogenous fibrinolysis at baseline but an impaired endothelial fibrinolytic response after venous occlusion. J Am Coll Cardiol, 2005; 45:30–34, doi:10.1016/j.jacc.2004.09.052.

To determine whether chronic inflammation of the vascular wall might be associated with an impaired activation of the fibrinolytic system, 50 patients were enrolled six months after their first myocardial infarction. Plasma levels of the inflammatory marker C-reactive protein (CRP) were determined at basal conditions, and the fibrinolytic parameters tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type-1 (PAI-1) were measured at basal conditions and after a standardized venous occlusion (VO) of the forearm. Patients with high CRP levels (Æ3 mg/l) showed a significantly higher t-PA activity at baseline compared with patients with medium (1 to 2.9 mg/l) and low (<1 mg/l) CRP levels (p < 0.005). In contrast, patients with low CRP levels showed a higher increase of t-PA activity (p < 0.05) and a higher reduction of PAI-1 activity during VO (p < 0.05) compared with patients with medium and high CRP levels. A multivariate analysis that included cardiovascular risk factors and medical treatment showed that CRP is an independent predictor of the t-PA response after a standardized VO. Chronic low-grade inflammation is associated with enhanced activation of endogenous fibrinolysis at baseline but a reduced fibrinolytic response to VO. This impaired endogenous fibrinolytic capacity might be an important contributor to the increased coronary event rate associated with elevated CRP levels.

79. The quote is found in Lisa Nainggolan, “First Evidence of Causal Link Between Diesel Fumes and Ischemia,” Sep. 17, 2007
September 17, 2007—A new study has shown that brief exposure to dilute diesel-exhaust fumes during exercise promotes myocardial ischemia and inhibits endogenous fibrinolytic capacity in men with stable coronary disease.[1] “Our findings point to ischemic and thrombotic mechanisms that may explain in part the observation that exposure to combustion-derived air pollution is associated with adverse cardiovascular events,” say Dr Nick Mills (Edinburgh University, Scotland) and colleagues in their paper in the September 13, 2007 issue of the New England Journal of Medicine.

Mills told heartwire that while a wealth of large-scale and robust studies have been conducted in the past five to 10 years looking at the association between air pollution and adverse cardiac outcomes, “these have been challenged because it’s been impossible to prove causality. What’s been missing in this field is an understanding of what the mechanism is that links exposure to adverse outcomes. We’re the first group to have conducted controlled exposures anywhere in the world, and our results are important because they provide strength to the observational studies, and they show that this is indeed a causal relationship we are talking about.”

The study is—Mills, N.L. Ischemic and Thrombotic Effects of Dilute Diesel-Exhaust Inhalation in Men with Coronary Heart Disease. N Engl J Med 2007; 357:1075–1082.

Although exposure to air pollution from traffic is associated with adverse cardiovascular events, the mechanisms for this association are unknown. To identify ischemic and thrombotic mechanisms that may explain in part the observation that exposure to combustion-derived air pollution is associated with adverse cardiovascular events, investigators conducted a controlled exposure to dilute diesel exhaust in patients with stable coronary heart disease to determine the direct effect of air pollution on myocardial, vascular, and fibrinolytic function.

In a double-blind, randomized, crossover study, 20 men with prior myocardial infarction were exposed, in two separate sessions, to dilute diesel exhaust (300 _g per cubic meter) or filtered air for 1 hour during periods of rest and moderate exercise in a controlled-exposure facility. During the exposure, myocardial ischemia was quantified by ST-segment analysis using continuous 12-lead electro-cardiography. Six hours after exposure, vasomotor and fibrinolytic function were assessed by means of intraarterial agonist infusions.

During both exposure sessions, the heart rate increased with exercise (P<0.001); the increase was similar during exposure to diesel exhaust and exposure to filtered air (P=0.67). Exercise-induced ST-segment depression was present in all patients, but there was a greater increase in the ischemic burden during exposure to diesel exhaust (–22±4 vs. –8±6 millivolt seconds, P<0.001). Exposure to diesel exhaust did not aggravate preexisting vasomotor dysfunction, but it did reduce the acute release of endothelial tissue plasminogen activator (P=0.009; 35% decrease in the area under the curve).

The investigators concluded that brief exposure to dilute diesel exhaust promotes myocardial ischemia and inhibits endogenous fibrinolytic capacity in men with stable coronary heart disease. Our findings point to ischemic and thrombotic mechanisms that may explain in part the observation that exposure to combustion-derived air pollution is associated with adverse cardiovascular events. (ClinicalTrials.gov number, NCT00437138 [ClinicalTrials.gov].)

Source Information

80. McConnell, R., Berhane, K., Gilliand, F., London, S.J., Islam, T., Gauderman, W.J., Avol, E., Margolis, H.G., & Peters, J.M.
Asthma in exercising children exposed to ozone: a cohort study
Lancet 2002; 359; 386–391

From the Southern California Children’s Study. Relevant numbers;
5762 children completed baseline questionnaires;
479 excluded because they were not at school when the questionnaire was administered;
883 excluded for a history of asthma;
312 excluded because of missing answers to “wheezing” questions;
26 excluded for chest illnesses such as cystic fibrosis:
527 excluded because they had less than one year of follow-up;
This left 3535 children with no initial history of asthma; 2752 of these had no history of wheezing; 1934 played sports; 273 played three or more team sports;
There were 46 low pollution communities (O₃ daytime mean 40.0 ppb); and 46 high pollution communities (O₃ mean 59.6 ppb). PM₁₀ twice as high in high ozone communities (43.3 vs 21.6) and PM_2.5 three times higher (21.4 vs 7.6). NO₂ three times higher in high ozone communities (29.2 vs 10.8 ppb).

It was shown that development of asthma prospectively was three times higher in children participating in more than 3 sports in high ozone communities, compared to children who did no sports in both communities or did fewer than 3 sports in high ozone communities. No differences in development of asthma if other pollutants were studied. Excellent discussion; 32 references. Convincing argument as to why standard cross-sectional comparisons might show no differences in prevalence of asthma.

81. See, e.g., Agricultural Research Services, U.S. Department of Agriculture, “Effects of Ozone Air Pollution on Plants,” http://www.ars.usda.gov/Main/docs.htm?docid=8453. Ozone penetrates stomata and destroys organic molecules in the plant tissue.

82. See H Sandermann, A. R. Wellburn & R.L. Heath (Eds), Forest Decline and Ozone: A Comparison of Controlled Chamber and Field Experiments, Springer Verlag, Berlin, 1997, explores the relationship between forest decline and ozone. It comprises a broad range of methods concerning field ecology, model ecosystem research, and basic physiological and biochemical research.

83. See e.g. Bell, M.L. et. Al. The Exposure-Response Curve for Ozone and Risk of Mortality and the Adequacy of Current Ozone Regulations. Environmental Health Perspectives Volume 114, Number 4, April 2006.

84. Shindell, D. (2007), Local and remote contributions to Arctic warming, Geophys. Res. Lett., 34, L14704, doi:10.1029/2007GL030221.

Investigating the relative impact of local and remote radiative forcing by tropospheric aerosols and ozone on Arctic climate using GISS climate model simulations, Shindell found that during boreal summer, Arctic climate is well-correlated with either the global or Arctic forcing. During other seasons, however, large-scale dynamics strongly influence the Arctic, so that the surface temperature response follows the global or Northern Hemisphere extratropical forcing much more closely. The decoupling is so strong that Arctic surface temperature trends often show the opposite sign to the local forcing. The analysis also demonstrates that ozone and aerosols affect Arctic climate more strongly per unit global forcing than well-mixed greenhouse gases, typically 2.5–5 times in non-summer seasons, making them powerful levers for influencing Arctic climate. However, controlling atmospheric burdens of climate-altering pollutants outside the polar region appears to be at least as important as controlling them within for mitigation of Arctic warming.

85. Schelegle ES, Siefkin AD, McDonald RJ. Time course of ozone-induced neutrophilia in normal humans. Am Rev Respir Dis 1991; 143:1353–58.

86. Graham DE, Henderson F, House DE. Neutrophil influx measured in nasal lavages of humans exposed to ozone. Arch Environ Health 1988;43:229–233.

87. Graham DE, Koren HS. Biomakers of inflammation in ozone-exposed humans. Am Rev Respir Dis 1990;142:152–156.

88. Bascom R, Naclerio RM, Fitzgerald TK, Kagey-Sobotka A, Proud D. Effect of ozone inhalation on the response to nasal challenge with antigen of allergic subjects. Am Rev Respir Dis 1990;142:594–601.

89. Bascom R, Naclerio RM, Fitzgerald TK, Kagey-Sobotka A, Proud D. Effect of ozone inhalation on the response to nasal challenge with antigen of allergic subjects. Am Rev Respir Dis 1990;142:594–601.

90. Smith CE, Koren HS, Graham DG, Johnson DA. Mast cell tryptase is increased in nasal and bronchial alveolar lavage fluids of humans after ozone exposure. Inhalation Toxicol 1993;5:117–127.

91. Lippman M. Health effects of ozone: a critical review. J Air Pollut Control Assoc 1989; 39:672–95.

92. Van Louveren HS:, Wagenaar S, Walvoort HC, Vos JG. Effect of ozone on the defense to a respiratory Listeria monocytogenes infection in the rat. Suppression of macrophage function on cellular immunity and aggravation of histopathology in lung and liver during infection. Toxicol Appl Pharmacol 1988; 94:374–93.

93. Gardner DE. Use of experimental airborne infections for monitoring altered host defenses. Environ Health Perspect 1982; 43:99–107.

94. Gilmour MI, Park P, Selgrade MK. Ozone-enhanced pulmonary infection with Streptococcus Zooepidemicus in mice: The role of alveolar macrophage function and capsular virulence factors. Am Rev Respir Dis 1993;147:753–60.

95. Gilmour MI, Selgrade MK. A comparison of the pulmonary defenses against Streptococcal infection in rats and mice following O₃ exposure: A possible mechanisms of disease resistance in rats. Toxicol Appl Pharmacol 1993.

96. Harkema JR, Plopper CG, Hyde DM, George JAS, Wilson DW, Dungworth DL. Response of the macaque nasal epithelium to ambient levels of ozone: a morphologic and morphometric study of the transitional and respiratory epithelium. Am J Pathol 1987;128:129–144.

97. Devlin RB, McDonnell WF, Mann R, Becker S, House DE, Schreinemachers D,Koren HS. Exposure of humans to ambient levels of ozone for 6.6 hours causes cellular and biochemical changes in the lung. Am J Respir Cell Molec Biol 1991;4:72–81.

98. Harder Sd, Harris DT, House D, Koren HS. Inhibition of human natural killer cell activity following in vitro exposure to ozone. Inhal Toxicol 1990;2:161–73.

99. Van Louveren HS; Wagenaar S, Walvoort HC, Vos JG. Effect of ozone on the defense to a respiratory Listeria monocytogenes infection in the rat. Suppression of macrophage function on cellular immunity and aggravation of histopathology in lung and liver during infection. Toxicol Appl Pharmacol 1988;94:374–393.

100. Gardner DE. Use of experimental airborne infections for monitoring altered host defenses. Environ Health Perspect 1982;43:99–107.

101. “Executive Summary,” Air Quality Criteria for Ozone and Related Photochemical Oxidants, United States Environmental Protection Agency, (Washington, DC: Office of Research and Development), February 1994.

102. McConnell, R., Berhane, K., Gilliand, F., London, S.J., Islam, T., Gauderman, W.J., Avol, E., Margolis, H.G., & Peters, J.M.
Asthma in exercising children exposed to ozone: a cohort study
Lancet 2002; 359; 386-391

From the Southern California Children’s Study. Relevant numbers;
5762 children completed baseline questionnaires;
479 excluded because they were not at school when the questionnaire was administered;
883 excluded for a history of asthma;
312 excluded because of missing answers to “wheezing” questions;
26 excluded for chest illnesses such as cystic fibrosis:
527 excluded because they had less than one year of follow-up;
This left 3535 children with no initial history of asthma; 2752 of these had no history of wheezing; 1934 played sports; 273 played three or more team sports;
There were 46 low pollution communities (O₃ daytime mean 40.0 ppb); and 46 high pollution communities (O₃ mean 59.6 ppb). PM₁₀ twice as high in high ozone communities (43.3 vs 21.6) and PM_2.5 three times higher (21.4 vs 7.6). NO₂ three times higher in high ozone communities (29.2 vs 10.8 ppb).

It was shown that development of asthma prospectively was three times higher in children participating in more than 3 sports in high ozone communities, compared to children who did no sports in both communities or did fewer than 3 sports in high ozone communities. No differences in development of asthma if other pollutants were studied. Excellent discussion; 32 references. Convincing argument as to why standard cross-sectional comparisons might show no differences in prevalence of asthma.

103. Ito, K., De Leon, S.F., Lippmann, M. Associations Between Ozone and Daily Mortality: Analysis and Meta-Analysis. Epidemiology. 16(4):446–457, July 2005.

There is ample evidence that short-term ozone exposure is associated with transient decrements in lung functions and increased respiratory symptoms, but the short-term mortality effect of such exposures has not been established.

A review and meta-analysis of short-term ozone mortality studies found a combined estimate of 0.39% (95% confidence interval = 0.26-0.51%) per 10-ppb increase in 1-hour daily maximum ozone for the all-age nonaccidental cause/single pollutant model (43 studies). Adjusting for the funnel plot asymmetry resulted in a slightly reduced estimate (0.35%; 0.23-0.47%). In a subset for which particulate matter (PM) data were available (15 studies), the corresponding estimates were 0.40% (0.27-0.53%) for ozone alone and 0.37% (0.20-0.54%) with PM in model. The estimates for warm seasons were generally larger than those for cold seasons. An additional time-series analysis for 7 U.S. cities (Chicago, Detroit, Houston, Minneapolis-St. Paul, New York City, Philadelphia, and St. Louis) found that including PM in the model did not substantially reduce the ozone risk estimates. However, the difference in the weather adjustment model could result in a 2-fold difference in risk estimates (eg, 0.24% to 0.49% in multicity combined estimates across alternative weather models for the ozone-only all-year case).

104. Hoek G, Schwartz JD, Groot B, Eilers P. Effects of ambient particulate matter and ozone on daily mortality in Rotterdam, The Netherlands. Arch Environ Health. 1997 Nov–Dec; 52(6):455–63.

The association between daily variations in all-cause mortality from 1983–1991 in Rotterdam, the Netherlands, and ambient air pollution was investigated. Twenty-four-hour average concentrations of total suspended particulates, Black Smoke, ozone, sulfur dioxide, and carbon monoxide were available on a daily basis. Every other day, total iron content in total suspended particulates samples was available. Poisson regression analysis was used to study associations between air pollution and mortality; generalized additive models were used to adjust for confounders (e.g., seasonal trends, weather). Daily mortality was associated most consistently with previous-day concentrations of total suspended particulates (relative risk = 1.05 for a change of 91 microg/m³) and ozone (relative risk = 1.06 for a change of 67 microg/m³). Total iron was associated less consistently with mortality than total suspended particulate mass was. The associations of mortality with ozone and total suspended particulates were independent of sulfur dioxide and carbon monoxide. The relative risks of total suspended particulates and particularly ozone were higher for subjects older than 78 y. The relationship between mortality and ozone did not deviate significantly from linear. The relationship between mortality and total suspended particulates was linear below 100 microg/m³ and leveled off at higher concentrations. If a threshold exists for the effects on mortality of these components, it exists at very low levels.

105. Stieb, D.M. et. Al. Association between ozone and asthma emergency department visits in Saint John, New Brunswick, Canada. Environ Health Perspect. 1996 December; 104(12): 1354–1360.

To assess the relationship of asthma emergency department (ED) visits to daily concentrations of ozone and other air pollutants in Saint John, New Brunswick, Canada, data on ED visits with a presenting complaint of asthma (n = 1987) were abstracted for the period 1984–1992 (May–September). Air pollution variables included ozone, sulfur dioxide, nitrogen dioxide, sulfate, and total suspended particulate (TSP); weather variables included temperature, humidex, dewpoint, and relative humidity. Daily ED visit frequencies were filtered to remove day of the week and long wave trends, and filtered values were regressed on air pollution and weather variables for the same day and the 3 previous days. The mean daily 1-hr maximum ozone concentration during the study period was 41.6 ppb. A positive, statistically significant (p < 0.05) association was observed between ozone and asthma ED visits 2 days later, and the strength of the association was greater in nonlinear models. The frequency of asthma ED visits was 33% higher (95% CI, 10-56%) when the daily 1-hr maximum ozone concentration exceeded 75 ppb (the 95th percentile). The ozone effect was not significantly influenced by the addition of weather or other pollutant variables into the model or by the exclusion of repeat ED visits. However, given the limited number of sampling days for sulfate and TSP, a particulate effect could not be ruled out. There was a significant association between ozone and asthma ED visits, despite the vast majority of sampling days being below then-current U.S. and Canadian standards.

106. Bell, M.L., McDermott, A., Zeger, S.L. Samet, J.M., and Dominici, F. Ozone and Short-term Mortality in 95 US Urban Communities, 1987–2000. JAMA. 2004;292:2372–2378.

Using analytical methods and databases developed for the National Morbidity, Mortality, and Air Pollution Study, a national average relative rate of mortality associated with short-term exposure to ambient ozone for 95 large US urban communities representing about 40% of the total US population from 1987–2000 was estimated. Distributed-lag models were used to estimate community-specific relative rates of mortality adjusted for time-varying confounders (particulate matter, weather, seasonality, and long-term trends) and hierarchical models for combining relative rates across communities to estimate a national average relative rate, taking into account spatial heterogeneity. A 10-ppb increase in the previous week’s ozone was associated with a 0.52% increase in daily mortality (95% posterior interval [PI], 0.27%–0.77%) and a 0.64% increase in cardiovascular and respiratory mortality (95% PI, 0.31%–0.98%). Effect estimates for aggregate ozone during the previous week were larger than for models considering only a single day’s exposure. Results were robust to adjustment for particulate matter, weather, seasonality, and long-term trends.

107. Alexandros Gryparis, A., et. al. Acute Effects of Ozone on Mortality from the “Air Pollution and Health A European Approach” Project. American Journal of Respiratory and Critical Care Medicine Vol 170. pp. 1080–1087, (2004).

In the Air Pollution and Health: A European Approach (APHEA2) project, the effects of ambient ozone concentrations on mortality were investigated. Data were collected on daily ozone concentrations, the daily number of deaths, confounders, and potential effect modifiers from 23 cities/areas for at least 3 years since 1990. Effect estimates were obtained for each city with city-specific models and were combined using second-stage regression models. No significant effects were observed during the cold half of the year. For the warm season, an increase in the 1-hour ozone concentration by 10 _g/m³ was associated with a 0.33% (95% confidence interval [CI], 0.17–0.52) increase in the total daily number of deaths, 0.45% (95% CI, 0.22–0.69) in the number of cardiovascular deaths, and 1.13% (95% CI, 0.62–1.48) in the number of respiratory deaths. The corresponding figures for the 8-hour ozone were similar. The associations with total mortality were independent of SO₂ and particulate matter with aerodynamic diameter less than 10 _m (PM₁₀) but were somewhat confounded by NO₂ and CO. Individual city estimates were heterogeneous for total (a higher standardized mortality rate was associated with larger effects) and cardiovascular mortality (larger effects were observed in southern cities). The dose-response curve of ozone effects on total mortality during the summer did not deviate significantly from linearity.

108. Agriculture and Agri-food Canada, Measuring plant response to ozone, http://www.agr.gc.ca/nlwis-snite/index_e.cfm?s1=pub&s2=ha_sa&page=73.

109. Reilly, S. et. al. Global economic effects of changes in crops, pasture, and forests due to changing climate, carbon dioxide, and ozone. Energy Policy 35 (11) 5370–5383 doi:10.1016/j.enpol.2006.01.040 (November 2007).

110. Sitch, S. Et. Al. “Indirect radiative forcing of climate change through ozone effects on the land-carbon sink. Nature 448, 791–794 (16 August 2007) | doi:10.1038/nature06059.

Tropospheric ozone is known to damage plants, reducing plant primary productivity and crop yields, yet increasing atmospheric carbon dioxide concentrations are thought to stimulate plant primary productivity. Increased carbon dioxide and ozone levels can both lead to stomatal closure, reducing the uptake of either gas, and in turn limiting the damaging effect of ozone and the carbon dioxide fertilization of photosynthesis. Researchers estimated the impact of projected changes in ozone levels on the land-carbon sink using a global land carbon cycle model modified to include the effect of ozone deposition on photosynthesis and to account for interactions between ozone and carbon dioxide through stomatal closure. They found a “significant suppression” of the global land-carbon sink as increases in ozone concentrations affect plant productivity. In consequence, more carbon dioxide accumulates in the atmosphere. They suggest that the resulting indirect radiative forcing by ozone effects on plants could contribute more to global warming than the direct radiative forcing due to tropospheric ozone increases.

111. Fuglestvedt, J.S. Climatic forcing of nitrogen oxides through changes in tropospheric ozone and methane; global 3D model studies. Atmospheric Environment,Volume 33, Issue 6, March 1999, Pages 961–977.

A three-dimensional global chemical tracer model and a radiation transfer model were used to study the role of NO_X emissions in global warming. Through production of tropospheric ozone, NO_X emissions lead to positive radiative forcing and warming. But by affecting the concentration of OH radicals, NO_X also reduces the levels of CH₄, thereby giving negative forcing and cooling. The lifetime of NO_X varies from hours to days, giving large spatial variations in the levels of NO_X. Geographical regions representing different chemical and physical conditions were selected to project chemical and radiative effects of reducing NO_X emissions by 20% in each region. Due to nonlinearities in the O₃ chemistry as well as differences in convective activity, there are large geographical differences in the effect of NO_X on O₃ as well as variations in the annual profile of the changes. The effect of NO_X emissions on methane is also found to depend on the localization of the emissions. The calculated ozone and methane forcing are of similar magnitude but of opposite sign. The methane effect acts on a global scale with a delay of approximately a decade, while the ozone effect is of regional character and occurs during weeks.

112. Fuglestvedt, J.S. Climatic forcing of nitrogen oxides through changes in tropospheric ozone and methane; global 3D model studies. Atmospheric Environment,Volume 33, Issue 6, March 1999, Pages 961–977.

A three-dimensional global chemical tracer model and a radiation transfer model were used to study the role of NO_X emissions in global warming. Through production of tropospheric ozone, NO_X emissions lead to positive radiative forcing and warming. But by affecting the concentration of OH radicals, NO_X also reduces the levels of CH₄, thereby giving negative forcing and cooling. The lifetime of NO_X varies from hours to days, giving large spatial variations in the levels of NO_X. Geographical regions representing different chemical and physical conditions were selected to project chemical and radiative effects of reducing NO_X emissions by 20% in each region. Due to nonlinearities in the O₃ chemistry as well as differences in convective activity, there are large geographical differences in the effect of NO_X on O₃ as well as variations in the annual profile of the changes. The effect of NO_X emissions on methane is also found to depend on the localization of the emissions. The calculated ozone and methane forcing are of similar magnitude but of opposite sign. The methane effect acts on a global scale with a delay of approximately a decade, while the ozone effect is of regional character and occurs during weeks.

113. Houghton, J. T. et al. (eds) Climate Change 2007: The Science of Climate Change (Cambridge Univ. Press, 2007).

114. Shindell, D., et. Al. Role of tropospheric ozone increases in 20^th-century climate change. J. Geophys. Res., 111, D08302, doi:10.1029/2005JD006348.

To simulate the warming effect of ozone, researchers employed the NASA Goddard Institute for Space Studies (GISS) chemistry model, using the spatial and temporal distribution of precursor emissions of tropospheric ozone from 1890 to 1990, finding that tropospheric ozone has contributed to the greater 20^th-century warming in the Northern Hemisphere extratropics compared with the tropics and in the tropics compared with the Southern Hemisphere extratropics. Additionally, ozone increased more rapidly during the latter half of the century than the former, causing more rapid warming during that time. Other climate forcings do not substantially accelerate warming rates in the tropics relative to other regions, suggesting that tropospheric ozone increases related to industrialization in the developing world have contributed to the accelerated tropical warming. During boreal, or northern, summer, tropospheric ozone causes enhanced warming (>0.50C) over polluted northern continental regions. Finally, the Arctic climate response to tropospheric ozone increases is large during fall, winter, and spring when ozone’s lifetime is comparatively long and pollution transported from mid-latitudes is abundant. The model indicates that tropospheric ozone could have contributed about 0.3° C annual average and about 0.4° C–0.5° C during winter and spring to the 20^th-century Arctic warming. According to the authors, “pollution controls could thus substantially reduce the rapid rate of Arctic warming.”

115. Matthes, S. et. al. Global impact of road traffic emissions on tropospheric ozone. Atmos. Chem. Phys., 7, 1707–1718, 2007.

Road traffic is one of the major anthropogenic emission sectors for NO_X , CO and NMHCs (non-methane hydrocarbons). To assess the global impact of 1990 road traffic emissions on the atmosphere, investigators applied ECHAM4/CBM, a general circulation model coupled to a chemistry module, which includes higher hydrocarbons. This improved on previous global modeling studies, which concentrated on road traffic NO_X and CO emissions only. Including NMHC emissions from road traffic that NMHC emissions from road traffic play a key role for the impact on ozone. They are responsible for (indirect) long-range transport of NO_X from road traffic via the formation of PAN, which is not found in a simulation without NMHC emissions from road traffic. Long-range transport of NMHC-induced PAN impacts on the ozone distribution in Northern Hemisphere regions far away from the sources, especially in arctic and remote maritime regions. In July total road traffic emissions (NO_X , CO and NMHCs) contribute to the zonally averaged ozone distribution by more than 12% near the surface in the Northern Hemisphere midlatitudes and arctic latitudes. In January, road traffic emissions contribute near the surface in northern and southern extratropics more than 8%. Sensitivity studies for regional emission show that effective transport of road traffic emissions occurs mainly in the free troposphere. In tropical latitudes of America up to an altitude of 200 hPa, global road traffic emissions contribute about 8% to the ozone concentration. In arctic latitudes NMHC emissions from road transport are responsible for about 90% of PAN increase from road transport, leading to a contribution to ozone concentrations of up to 15%.

116. Niemeir, U. et. al. Global impact of road traffic on atmospheric chemical composition and on ozone climate forcing. Journal of Geophysical Research, Vol. 111, D09301,doi:10.1029/2005JD006407, 2006.

Automobile emissions are known to contribute to local air pollution and to photochemical smog in urban areas. The impact of road traffic on the chemical composition of the troposphere at the global scale and on climate forcing is less well quantified. Calculations performed with the chemical transport MOZART-2 model show that the concentrations of ozone and its precursors (NO_X, CO, and hydrocarbons) are considerably enhanced in most regions of the Northern Hemisphere in response to current surface traffic. During summertime in the Northern Hemisphere, road traffic has increased the zonally averaged ozone concentration by more than 10% in the boundary layer and in the extratropics by approximately 6% at 500 hPa and 2.5% at 300 hPa. The summertime surface ozone concentrations have increased by typically 1–5 ppbv in the remote regions and by 5–20 ppbv in industrialized regions of the Northern Hemisphere. The corresponding ozone-related radiative forcing is 0.05 Wm-2. In order to assess the sensitivity of potential changes in road traffic intensity, two additional model cases were considered, in which traffic-related emissions in all regions of the world were assumed to be on a per capita basis the same as in Europe and in the United States, respectively. In the second and most dramatic case, the surface ozone concentration increases by 30–50 ppbv (50–100%) in south Asia as compared to the present situation. Under this assumption, the global radiative forcing due to traffic-generated ozone reaches 0.27 Wm-2.

117. Houghton, J. T. et al. (eds) Climate Change 2007: The Science of Climate Change (Cambridge Univ. Press, 2007).

118. de F. Forster, P.M. et al. Further Estimates of Radiative Forcing Due to Tropospheric Ozone Changes. Geophys. Res. Lett., 23(23), 3321–3324, Nov. 15, 1996.

Estimates made by two 2-D (latitude-height) chemical transport models show large uncertainty, but continue to support the case that tropospheric ozone changes make a substantial contribution (about 15%) to the total greenhouse gas radiative forcing.

119. Volz, A. & Kley, D. Evaluation of the Montsouris series of ozone measurements made in the nineteenth century. Nature 332, 240–242 (17 March 1988); doi:10.1038/332240a0

Questions regarding pre-industrial or ‘background’ ozone concentrations have led to the search for data from the early days of ozone monitoring, during the second half of the last century. Unfortunately, most measurements were then made using Schönbein test paper, giving only semi-quantitative information due to poor standardization and the influence of humidity and wind speed on its sensitivity. Volz and Kley reinvestigated a set of ozone measurements gathered at the Observatoire de Montsouris, located on the outskirts of Paris, where a quantitative method was established in 1876 and used continuously for 34 years. The evaluation of the technique, together with the analysis of nearly 3,000 of the original daily measurements that previously remained unnoticed in a statistical bulletin of the City of Paris, provides conclusive evidence that ozone levels in central Europe 100 years ago averaged 10 p.p.b. and exhibited a seasonal variation, with a maximum during the spring months. Comparisons with modern data show that ozone levels in rural areas have more than doubled over the past century and that the tropospheric ozone budget is now strongly influenced by photochemical production due to increased levels of NO_X.

120. Volz, A. & Kley, D. Evaluation of the Montsouris series of ozone measurements made in the nineteenth century. Nature 332, 240–242 (17 March 1988); doi:10.1038/332240a0

Questions regarding pre-industrial or ‘background’ ozone concentrations have led to the search for data from the early days of ozone monitoring, during the second half of the last century. Unfortunately, most measurements were then made using Schönbein test paper, giving only semi-quantitative information due to poor standardization and the influence of humidity and wind speed on its sensitivity. Volz and Kley reinvestigated a set of ozone measurements gathered at the Observatoire de Montsouris, located on the outskirts of Paris, where a quantitative method was established in 1876 and used continuously for 34 years. The evaluation of the technique, together with the analysis of nearly 3,000 of the original daily measurements that previously remained unnoticed in a statistical bulletin of the City of Paris, provides conclusive evidence that ozone levels in c