1. I. I.Air Pollution – Sources & Effects Most local air pollution associated with cities, esp. large cities and industrial centers Average concentration of airborne particles in urban areas ~10x concentration in rural areas Major cities – air pollution causes thousands of deaths each year Los Angeles – 6000 New York – 4000 Detroit – 2000 Mexico City – Air quality so severe that some people estimate breathing is equivalent to smoking two packs of cigarettes a day Many air pollutants are hygroscopic Combine with water and promote fog formation Particulate matter can affect local precipitation Boulder, CO – Power plant produced fly ash aerosols and induced snowfall

2. II. II.Air Pollution – Components Primary Problematic in the form in which they’re produced Ex – Lead, carbon monoxide Secondary Require modification Ex – Ozone Many are components of photochemical smog (react chemically with light) Legislation addressing air pollution requires consideration of both primary and secondary pollutants Clean Air Act – 1970Clean Air Act Clean Air Act Amendments – 1990 EPA – NAAQS for six criteria pollutants

4. II. II.Air Pollution – Components A. A.Particulate Matter 1. 1.Sources Combustion of fossil fuels, especially coal Mobile sources – Cars, trucks Stationary sources – Power plants, industrial furnaces, wood stoves 2. 2.Effects By the 1950s, air quality in London had deteriorated so much that incidences of death due to pollution weren’t uncommon 1952 – “Killer Smog” in London  4000+ deaths Health – Respiratory impairment, lung damage, lung cancer Especially children, elderly, people with chronic respiratory problems Acidic PM can damage structures, reduce visibility

6. NYC - 1963 LA - 1943

7. II. II.Air Pollution – Components A. A.Particulate Matter 3. 3.Trends EPA Standards Pre-1987 – TSP (Total Suspended Particulates) Post-1987 – PM 10 (Particles < 10 μm) Post-1997 – PM 2.5 (Particles < 2.5 μm) NAAQS for PM 10 Annual average = 50 μg m -3 (revoked Dec 2006) Daily peak = 150 μg m -3 NAAQS for PM 2.5 Annual average = 15 μg m -3 Daily peak = 35 μg m -3

9. http://www.epa.gov/air/airtrends 1990-2009: Direct PM2.5 emissions down 50% 1990-2009: Direct PM10 emissions down 67%

10. II. II.Air Pollution – Components B. B.Carbon Monoxide Colorless, odorless gas Produced by incomplete combustion of fossil fuels (too little O 2 supplied in a normally tuned engine) 1. 1.Sources About 56% of CO emissions nationwide from on-road motor vehicles (24% from non-road vehicles) In cities, 85-95% of CO from motor vehicles Diesel engines typically produce less CO but more PM than gasoline engines Alternative to complete combustion of fuel is combustion of exhaust Produces hazardous amounts of heat Combustion temperature can be lowered using catalyst Chemical catalysts poisoned by lead

11. II. II.Air Pollution – Components B. B.Carbon Monoxide 2. 2.Effects CO binds to hemoglobin in place of oxygen Affinity for CO ~ 200x higher than for O 2 Continued exposure can lead to Impairment of vision Difficulty estimating time Reduced manual dexterity Poor learning ability Difficulty performing complex tasks Greater risk of heart attacks in people with certain forms of heart disease (e.g. angina) Contributes to formation of ground-level ozone

12. 1990-2008 Vehicle miles traveled increased 36%

13. II. II.Air Pollution – Components C. C.Nitrogen Oxides (NO x ) Principally NO 2 Highly reactive reddish-brown gas Play a major role in the formation of ozone, PM, haze and acid rain Important component of photochemical smog 1. 1.Sources Forms from FF combustion at high temperatures Mobile – Cars & trucks (58%) Stationary – Power plants (34%), home heaters, gas stoves, industrial plants (8% total) Formation could be controlled by using pure oxygen for combustion (impractical and dangerous) Formation reduced by low-temperature combustion

14. Denver

15. II. II.Air Pollution – Components C. C.Nitrogen Oxides (NO x ) 2. 2.Effects Strong oxidizing agent Reacts readily in air to form nitric acid and nitrates Health Irritates lungs and lower resistance to respiratory infections Lung damage Environment Damages plant foliage, impairs growth Precursor of ground-level ozone, PM, smog Contributes to acid rain - Leaching of minerals from soil - Acidification of lakes and waterways Contributes to eutrophication of lakes & waterways Contributes to global warming (N 2 O)