1. Air Pollution

2. South Asia’s Massive Brown Cloud 1. Areas impacted: much of India, Bangladesh, & industrial heart of China 2. Chemical composition  dust particles, smoke, & ash resulting from drought, clearing & burning forests  soot from burning wood & dung  Acidic compounds from vehicle exhaust  Emissions from coal burning power plants, smelters, & waste incinerators 3. China and India need stricter air pollution standards

3. Layers of the Atmosphere 1. Troposphere  Weather  Contains the majority of molecules 2. Stratosphere  Protective ozone layer; shields from UV radiation 3. Mesophere  Coldest layer  Meteors vaporize in the mesosphere 4. Thermosphere  Highest temperatures 5. Exosphere  Lowest atmospheric pressure

4. Layers of the Atmosphere  Density decreases with altitude  Atmospheric pressure decreases with altitude

5. The Stratosphere Is Our Global Sunscreen 1. Stratosphere  Similar composition to the troposphere, with 2 exceptions Much less water O 3, ozone layer 2. Ozone layer Filters 95% of harmful UV radiation Allows us and other life to exist on land

6. Air Pollution Comes from Natural & Human Sources 1. Air pollution  Concentrations high enough to harm human health or alter climate 2. Natural sources  Dust blown by wind  Pollutants from wildfires and volcanoes  Volatile organics released by plants 3. Anthropogenic sources: mostly in industrialized and/or urban areas  Stationary sources: power plants and industrial facilities  Mobile sources: motor vehicles

7. Some Pollutants in the Atmosphere Combine to Form Other Pollutants 1. Primary pollutants: Emitted directly into the air  EX: SO 2 released by coal burning power plants 2. Secondary pollutants  From reactions of primary pollutants  SO 2 + H 2 0  H 2 SO 4 3. Air quality improving in developed countries 4. Less-developed countries face big problems  Indoor pollution: big threat to the poor Burn charcoal or dung in open fire pits Cigarette smoke Work in poorly ventilated & highly polluted places

8. Fig. 18-5, p. 469 Primary Pollutants CO CO 2 Secondary Pollutants SO 2 NO CH 4 and most other hydrocarbons CH 4 and most other hydrocarbons SO 3 Most suspended particles H2O2H2O2 H2O2H2O2 H 2 SO 4 PANs Most NO 3 – and SO 4 2– salts Natural Source Stationary Human Source Mobile NO 2 O3O3 O3O3 HNO 3 Sources and Types of Air Pollutants

9. Indoor Air Pollution in Bangladesh Fig. 18-6, p. 469

10. Major Outdoor Air Pollutants 1. Carbon oxides  Carbon monoxide (CO) Colorless, odorless, tasteless Combines irreversibly with hemoglobin; can cause death CO accumulated in poorly ventilated areas  Carbon dioxide (CO 2 ) 93% in atmosphere results from natural processes Biggest problem is global warming 2. Nitrogen oxides (NO) and nitric acid (HNO 3 )  Motor vehicle exhaust (N 2 & O 2 combine under high combustion temps & from coal burning power plants  NO reacts with oxygen gas to form NO 2 a reddish-brownish gas that forms photochemical smog  NO 2 reacts with water vapor to form HNO 3 & NO 3 -

11. 3. Sulfur dioxide (SO 2 ) and sulfuric acid (H 2 SO 4 )  Colorless gas with irritating odor  ⅓ comes from natural sources (sulfur cycle)  ⅔ comes from anthropogenic sources (burning coal in coal burning power plants  SO 2 combines with H 2 O in atmosphere to form H 2 SO 4 (sulfuric acid) acid precipitation  Acid rain lowers soil and water pH At low pH Ca & Mg become unavailable to plants AT low pH AL & Fe become highly available & reach toxic levels in plants Major Outdoor Air Pollutants

12. 4. Particulates  Suspended particulate matter  Includes dust & soot 5. Ozone (O 3 )  Colorless & highly reactive gas  Major component of photochemical smog  Human impact: respiratory distress 6. Volatile organic compounds (VOCs)  Hydrocarbons (CH 4 ) and terpenes (from plants)  Car emissions and emissions from gasoline  CH 4 : landfills, swamp, rice paddies

13. Lead : a Highly Toxic Pollutant 1. In air, water, soil, plants, animals 2. Does not break down in the environment 3. Human health and environmental impact  Neurotoxin; harms nervous system  Children most vulnerable  Can cause death, mental retardation (lowers IQ by 7.4 pts), paralysis 4. Reduction of lead (Pb)  Unleaded gasoline (phase out completed by 1986)  Unleaded paint (greatly reduced amount in paint) 5. Remaining Sources of lead  Lead leached out of water pipes & faucets containing lead parts  Need global ban on lead in gasoline and paint

14. Solutions: Lead Poisoning, Prevention and Control Fig. 18-8, p. 472

15. Burning Coal Produces Industrial Smog 1. Industrial smog: unhealthy mix of SO 2, suspended droplets of H 2 SO 4, & variety of suspended solid particles  Reduction of this smog in urban cities of the United States 2. China and smog (16 of 20 worst polluted cities in the world)  Need strong standards, especially for coal burning

16. Pollutants Form from Burning Coal & Oil, Leading to Industrial Smog Fig. 18-9, p. 474

17. Sunlight Plus Cars Equals Photochemical Smog 1. Photochemical Smog  VOCs + NO x + Heat + Sunlight yields  Ground level O 3 and other photochemical oxidants  Aldehydes 2. Human health and environmental impact 3. Cities that experience a lot of photochemical smog:  Los Angeles, Salt lake City, Bangkok, Santiago, Sydney, Sao Paulo, Mexico City

18. Several Factors Can Decrease or Increase Outdoor Air Pollution 1. Outdoor air pollution may be decreased by 1.Settling of particles due to gravity 2.Rain, snow, and wind 3.Salty sea spray from the ocean 4.Chemical reactions 2. Outdoor air pollution may be increased by 1.Urban buildings 2.Hills and mountains 3.High temperatures 4.Emissions of VOCs from certain trees and plants 5.Grasshopper effect 6.Temperature inversions Warm air above cool air prevents mixing Mexico City and Los Angeles

19. Natural Capital Degradation: Acid Deposition Fig. 18-14, p. 477

20. Current and Possible Future Acid Rain Problem Areas Fig. 18-15, p. 478

21. Harmful Effects of Acid Deposition 1. Human health  Respiratory disorders  Toxins in fish 2. Release of toxic metals (Al & Fe) 3. Aquatic ecosystems affected  Lowers pH and kills organisms 4. Leaching of soil nutrients  Lower crop yields  Forest damage 5. Damage to buildings, statues, and monuments

22. Solutions: Acid Deposition Fig. 18-17, p. 480

23. Indoor Air Pollution 1. Developing countries  Indoor burning of wood, charcoal, dung, crop residues, coal  Poor suffer the greatest risk 2. Developed countries  Indoor air pollution is greater than outdoor air pollution 3. Why?  11 of the common air pollutants higher inside than outside  Greater in vehicles than outside  Health risks magnified: people spend 70–98% of their time is indoors or in cars

24. Burning Wood Indoors in India Burning wood to cook food inside this dwelling in India (right) exposes the occupants to dangerous levels of air pollution.

25. Indoor Air Pollution 1. Who is at greatest risk from indoor air pollution?  Children under 5 and the elderly  Sick  Pregnant women  People with respiratory disorders or heart problems  Smokers  Factory workers 2. Four most dangerous indoor air pollutants  Tobacco smoke  Formaldehyde  Radioactive radon-222 gas  Very small particles

26. Indoor Air Pollution 1. Other possible indoor air pollutants  Pesticide residue  Pb particles  Living organisms and their excrements  E.g., Dust mites and cockroach droppings  Airborne spores of molds and mildews 2. Sick-building syndrome: health effects caused by air pollutants  Headaches, nausea, dizziness, respiratory problems, chronic fatigue, burning eyes, dry skin

27. Sources & Paths of Entry for Indoor Radon- 222 Gas  Colorless, odorless, radioactive gas  Produced by radioactive decay of uranium -238  Seeps upward through soil  In buildings above uranium deposits, it can enter through cracks in foundation & walls  Once inside homes, it can build up to high levels  Decays into Polonium -210 which can lead to lung cancer

28. Laws and Regulations 1. United States  Clean Air Acts: 1970, 1977, and 1990 created regulations enforced by states and cities 2. EPA  National ambient air quality standards for 6 outdoor pollutants  National emission standards for 188 hazardous air pollutants (HAPs) Toxic Release Inventory (TRI) Requires refineries, power plants, mines, chemical manufactures, & factories to report their releases and water management methods for the 667 toxic chemicals

29. Improving Air Pollution in the US 1. Rely on prevention of pollution, not cleanup 2. Sharply reduce emissions from power plants, industrial plants, and other industry 3. Raise fuel-efficiency for cars, SUVs, and light trucks 4. Better regulation of emissions of motorcycles and two- cycle gasoline engines 5. Regulate air pollution for oceangoing ships in American ports 6. Regulate emissions at U.S. airports 7. Sharply reduce indoor pollution 8. Increased and more accurate monitoring of air pollutants

30. Using the Marketplace to Reduce Outdoor Air Pollution 1. Emission trading or cap-and-trade program  Mixed reactions to program  SO 2 emissions down significantly  NO x now in effect  Mercury plan strongly opposed for creating toxic hotspots 2. Many problems with making cap-and-trade effective

31. Three Big Ideas 1.Outdoor air pollution, in the forms of industrial smog, photochemical smog, and acid deposition, and indoor air pollution are serious global problems. 2.Each year, at least 2.4 million people die prematurely from the effects of air pollution; indoor air pollution, primarily in less-developed countries, causes about two-thirds of those deaths. 3.We need to put our primary emphasis on preventing outdoor and indoor air pollution throughout the world.