1. © 2011 Pearson Education, Inc. Air Pollution

2. © 2011 Pearson Education, Inc. The atmosphere Atmosphere = the thin layer of gases around Earth -Provides oxygen -Absorbs radiation and moderates climate -Transports and recycles water and nutrients -78% N 2, 21% O 2 Minute concentrations of permanent (remain at stable concentrations) gases -Variable gases = varying concentrations across time and place Human activity is changing the amount of some gases -CO 2, methane (CH 4 ), ozone (O 3 )

3. © 2011 Pearson Education, Inc. The atmosphere’s composition

4. © 2011 Pearson Education, Inc. The atmosphere drives weather and climate Weather and climate involve the physical properties of the troposphere -Temperature, pressure, humidity, cloudiness, wind Weather = specifies atmospheric conditions over short time periods and within small geographic areas Climate = patterns of atmospheric conditions across large geographic regions over long periods of time Mark Twain said, “Climate is what we expect; weather is what we get”

5. © 2011 Pearson Education, Inc. Air masses produce weather Front = the boundary between air masses that differ in temperature, moisture, and density Warm front = boundary where warm, moist air replaces colder, drier air Cold front = where colder, drier air displaces warmer, moister air Warm fronts produce light rain Cold fronts produce thunderstorms

6. © 2011 Pearson Education, Inc. Air masses have different pressures High-pressure system = air that descends because it is cool -It spreads outward as it nears the ground -Brings fair weather Low-pressure system = warm air rises and draws air inward toward the center of low pressure -Rising air expands and cools -It brings clouds and precipitation

7. © 2011 Pearson Education, Inc. Thermal (temperature) inversion Thermal inversion = a layer of cool air occurs beneath warm air Inversion layer = the band of air where temperature rises with altitude -Denser, cooler air at the bottom of the layer resists mixing Inversions trap pollutants in cities surrounded by mountains Air temperature decreases as altitude increases - Warm air rises, causing vertical mixing

8. © 2011 Pearson Education, Inc. Global wind patterns Atmospheric cells interact with Earth’s rotation to produce global wind patterns -As Earth rotates, equatorial regions spin faster Coriolis effect = the apparent north-south deflection of air currents of the convective cells -Results in curving global wind patterns called the doldrums, trade winds, and westerlies

9. © 2011 Pearson Education, Inc. Climate patterns and moisture distribution

10. © 2011 Pearson Education, Inc. Outdoor air pollution Air pollutants = gases and particulate material added to the atmosphere -Can affect climate or harm people or other organisms Air pollution = the release of pollutants Outdoor (ambient) air pollution = pollution outside -Has recently decreased due to government policy and improved technologies in developed countries -Developing countries and urban areas still have significant problems

11. © 2011 Pearson Education, Inc. Natural sources pollute: volcanoes Release particulate matter, sulfur dioxide, and other gases -Can remain for months or years Aerosols = fine droplets of sulfur dioxide, water, oxygen -Reflect sunlight back to space -Cool the atmosphere and surface Volcanoes are one source of natural air pollution, as shown by the Mount Saint Helens eruption in 1980

12. © 2011 Pearson Education, Inc. Natural sources pollute: fires Fires pollute the atmosphere with soot and gases Over 60 million ha (150 million acres) of forests and grasslands burn per year Human influence makes fires worse -Fuel buildup from fire suppression, development in fire-prone areas, “slash-and-burn” agriculture -Climate change will increase drought and fires In 1997, unprecedented forest fires sickened 20 million and caused a plane to crash

13. © 2011 Pearson Education, Inc. Wind over arid land sends huge amounts of dust aloft -Even across oceans Businesses, schools, and governments close Unsustainable farming and grazing promote: -Erosion -Desertification Natural sources pollute: dust storms

14. © 2011 Pearson Education, Inc. We create outdoor air pollution Air pollution comes from mobile or stationary sources Point sources = specific spots where large quantities of pollutants are discharged (power plants and factories) Non-point sources = more diffuse, consisting of many small sources (automobiles) Primary pollutants = directly harmful and can react to form harmful substances (soot and carbon monoxide) Secondary pollutants = form when primary pollutants interact or react with components of the atmosphere -Tropospheric ozone and sulfuric acid

15. © 2011 Pearson Education, Inc. Pollutants exert local and global effects Residence time = the time a pollutant stays in the atmosphere Pollutants with brief residence times exert localized impacts over short time periods -Particulate matter, automobile exhaust Pollutants with long residence times exert regional or global impacts -Pollutants causing climate change or -ozone depletion

16. © 2011 Pearson Education, Inc. Legislation addresses pollution Air Pollution Control Act (1963) funded research and encouraged emissions standards The Clean Air Act of 1970 -Set standards for air quality, limits on emissions -Provided funds for pollution-control research -Allowed citizens to sue parties violating the standards The Clean Air Act of 1990 strengthened regulations for auto emissions, toxic air pollutants, acidic deposition, stratospheric ozone depletion -Introduced emissions trading for sulfur dioxide

17. © 2011 Pearson Education, Inc. The EPA sets standards The EPA sets nationwide standards for emissions and concentrations of toxic pollutants States monitor air quality -They develop, implement, and enforce regulations -They submit plans to the EPA for approval The EPA takes over enforcement if plans are inadequate Criteria pollutants = pollutants that pose especially great threats to human health -Carbon monoxide, sulfur dioxide, nitrogen dioxide, tropospheric ozone, particulate matter, lead

18. © 2011 Pearson Education, Inc. Criteria pollutants: CO and SO 2 Carbon monoxide (CO) = colorless, odorless gas -Produced primarily by incomplete combustion of fuel -From vehicles and engines, industry, waste combustion, residential wood burning -Poses risk to humans and animals, even in small concentrations Sulfur dioxide (SO 2 ) = colorless gas with a strong odor -Coal emissions from electricity generation, industry -Can form acid precipitation

19. © 2011 Pearson Education, Inc. Criteria pollutants: NO 2 Nitrogen dioxide (NO 2 ) = a highly reactive, foul- smelling reddish brown gas -Nitrogen oxides (NO x ) = formed when nitrogen and oxygen react at high temperatures in engines -Vehicles, industrial combustion, electrical utilities -Contribute to smog and acid precipitation

20. © 2011 Pearson Education, Inc. Criteria pollutants: tropospheric ozone Tropospheric ozone (O 3 ) = a colorless gas with a strong odor -Results from interactions of sunlight, heat, nitrogen oxides, and volatile carbon-containing chemicals -A secondary pollutant -A major component of smog -Participates in reactions that harm tissues and cause respiratory problems -The pollutant that most frequently exceeds EPA standards

21. © 2011 Pearson Education, Inc. Criteria pollutants: particulate matter and lead Particulate matter = suspended solid or liquid particles -Primary pollutants: dust and soot -Secondary pollutants: sulfates and nitrates -Damages respiratory tissue when inhaled -From dust and combustion processes Lead = in gasoline and industrial metal smelting -Bioaccumulates and damages the nervous system -Banned in gasoline in developed, but not in developing, countries

22. © 2011 Pearson Education, Inc. Areas in the U.S. fail air quality standards Many Americans live in areas with unhealthy levels of criteria pollutants

23. © 2011 Pearson Education, Inc. U.S. air pollution In 2008, the U.S. emitted 123 million tons of the six monitored pollutants The average U.S. driver emits 6 metric tons of CO 2 /yr as well as other pollutants!

24. © 2011 Pearson Education, Inc. We have reduced air pollution Total emissions of the six monitored pollutants have declined 60% since the Clean Air Act of 1970 -Despite increased population, energy consumption, miles traveled, and gross domestic product

25. © 2011 Pearson Education, Inc. We reduced emissions and improved the economy Technology and federal policies Cleaner-burning engines and catalytic converters Permit-trading programs and clean coal technologies reduce SO 2 emissions Scrubbers = chemically convert or physically remove pollutants before they leave smokestacks Phaseout of leaded gasoline

26. © 2011 Pearson Education, Inc. Toxic substances pose health risks Toxic air pollutants = substances that cause: -Cancer, reproductive defects -Neurological, developmental, immune system, or respiratory problems The EPA regulates 188 toxic air pollutants from metal smelting, sewage treatment, industry, etc. Include heavy metals, diesel, urban hazards Clean Air Act regulations helped reduce emissions by more than 35% since 1990

27. © 2011 Pearson Education, Inc. U.S. health risks vary geographically Nationwide cancer risks Non-cancerous respiratory ailments

28. © 2011 Pearson Education, Inc. Pollution in developing nations is high More people own cars Smog in Beijing surrounds an Olympic stadium

29. © 2011 Pearson Education, Inc. Air pollution in China The government is trying to decrease pollution -Shutting down heavily polluting factories and mines -Phasing out some subsidies for polluting industries -Installing pollution controls in factories -Encouraging renewable and nuclear energy -Mandating cleaner burning fuels Air is improving in Beijing but not in other places Asian (Atmospheric) Brown Cloud = a 2-mile-thick layer of pollution over southern Asia -Decreased plant productivity, increased flooding, etc.

30. © 2011 Pearson Education, Inc. Air quality is a rural issue, too Airborne pesticides from farms Industrial pollutants from cities, factories, and power plants Feedlots, where cattle, hogs, or chickens are raised in dense concentrations -Voluminous amounts of dust, methane, hydrogen sulfide, and ammonia -Also create objectionable odors -People living or working nearby have high rates of respiratory illness

31. © 2011 Pearson Education, Inc. Smog: our most common air quality problem Smog = an unhealthy mixture of air pollutants over urban areas Sulfur in burned coal combines with oxygen to form sulfuric acid Industrial (gray air) smog = industries burn coal or oil -Regulations in developed countries reduced smog Coal-burning industrializing countries face health risks -Coal and lax pollution control Smog in Donora killed 21 people and sickened 6,000

32. © 2011 Pearson Education, Inc. Photochemical (brown air) smog Produced by a series of reactions -Formed in hot, sunny cities surrounded by mountains Light-driven reactions of primary pollutants and atmospheric compounds -Morning traffic releases NO and VOCs -Irritates eyes, noses, and throats Los Angeles smog kills 3,900/year and costs $28 billion/year High levels of NO 2 cause photochemical smog to form a brown haze over cities

33. © 2011 Pearson Education, Inc. Industrial smogPhotochemical smog Creation of industrial and photochemical smog

34. © 2011 Pearson Education, Inc. We can reduce smog Regulations require new cars to have catalytic converters Require cleaner industrial facilities -Close those that can’t improve Financial incentives to replace aging vehicles -Restricting driving Vehicle inspection programs (“smog checks”) Reduce sulfur in diesel; remove lead in gasoline Electronic pollution indicator boards raise awareness But increased population and cars can wipe out advances

35. © 2011 Pearson Education, Inc. Synthetic chemicals deplete stratospheric ozone Ozone layer = ozone in the lower stratosphere -Blocks incoming ultraviolet (UV) radiation -Protecting life from radiation’s damaging effects Ozone-depleting substances = human-made chemicals that destroy ozone by splitting its molecules apart Halocarbons = human-made compounds made from hydrocarbons with added chlorine, bromine, or fluorine Chlorofluorocarbons (CFCs) = a halocarbon used as refrigerants, in fire extinguishers, in aerosol cans, etc. -Releases chlorine atoms that split ozone

36. © 2011 Pearson Education, Inc. CFCs destroy ozone CFCs are inert (don’t react) CFCs remain in the stratosphere for a century UV radiation breaks CFCs into chlorine and carbon atoms The chlorine atom splits ozone Ozone hole = decreased ozone levels over Antarctica One chlorine atom can destroy 100,000 ozone molecules

37. © 2011 Pearson Education, Inc. The Antarctic ozone hole High-altitude polar stratospheric clouds form during the dark, frigid winter Nitric acid in clouds splits chlorine off of CFCs -A polar vortex (swirling winds) traps chlorine -UV radiation in September (spring) sunshine dissipates the clouds and releases the chlorine -The chlorine destroys the ozone -December’s warmer air shuts down the polar vortex -Ozone-poor air diffuses, while ozone-rich air enters

38. © 2011 Pearson Education, Inc. The Montreal Protocol Montreal Protocol = 196 nations agreed to cut CFC production in half by 1998 Follow-up agreements deepened cuts, advanced timetables, and addressed other ozone-depleting chemicals -Industry shifted to safer, inexpensive, and efficient alternatives Challenges still face us -CFCs will remain in the stratosphere for a long time -Nations can ask for exemptions to the ban

39. © 2011 Pearson Education, Inc. The Montreal Protocol is a success It is considered our biggest environmental success story Research developed rapidly, along with technology Policymakers included industry in helping solve the problem Implementation of the plan allowed an adaptive management strategy -Strategies responded to new scientific data, technological advances, and economic figures The Montreal Protocol can serve as a model for international environmental cooperation

40. © 2011 Pearson Education, Inc. Protecting the ozone layer International agreements reduced ozone-depleting substances The hole in the ozone has stopped growing

41. © 2011 Pearson Education, Inc. Acid deposition Acid deposition is another transboundary issue Acidic deposition = the deposition of acid, or acid- forming pollutants from the atmosphere onto Earth’s surface Acid rain = precipitation containing acid -Rain, snow, sleet, hail Atmospheric deposition = the wet or dry deposition on land of pollutants (mercury, nitrates, organochlorines) -From automobiles, electric utilities, industrial facilities

42. © 2011 Pearson Education, Inc. Burning fossil fuels produces acid rain Burning fossil fuels releases sulfur dioxide and nitrogen oxides -These compounds react with water, oxygen, and oxidants to form sulfuric and nitric acids

43. © 2011 Pearson Education, Inc. Impacts of acid deposition Nutrients are leached from topsoil Soil chemistry is changed Metal ions (aluminum, zinc, etc.) are converted into soluble forms that pollute water Affects surface water and kills fish Damages agricultural crops Erodes stone buildings, corrodes cars, erases writing on tombstones

44. © 2011 Pearson Education, Inc. pH of precipitation in the U.S. Many regions of acidification are downwind of major sources of pollution The acid-neutralizing capacity of soil, rock, or water impacts the severity of acid rain’s effects

45. © 2011 Pearson Education, Inc. We have begun to address acid deposition Reducing acid deposition involves reducing the pollution that contributes to it The Clear Air Act of 1990 established an emissions trading program for sulfur dioxide -Benefits outweighed costs 40:1 New technologies such as scrubbers have helped Acid deposition is worse in the developing world -Especially in China, which burns coal in factories lacking pollution control equipment

46. © 2011 Pearson Education, Inc. Indoor air pollution Indoor air pollution = in workplaces, schools, and homes -Health effects are greater than from outdoor pollution The average U.S. citizen spends 90% of the time indoors -Exposed to synthetic materials that have not been comprehensively tested Being environmentally prudent can make it worse -To reduce heat loss and improve efficiency, ventilation systems were sealed off -Windows do not open, trapping pollutants inside

47. © 2011 Pearson Education, Inc. Indoor air pollution in the developing world Stems from burning wood, charcoal, dung, crop wastes with little to no ventilation Fuel burning pollution causes 1.6 million deaths/year -Soot and carbon monoxide -Pneumonia, bronchitis, lung cancer, allergies, cataracts, asthma, heart disease, etc.

48. © 2011 Pearson Education, Inc. Tobacco smoke and radon The most dangerous indoor pollutants in developed nations Secondhand smoke from cigarettes is very dangerous -Contains over 4,000 chemical compounds -Causes eye, nose, and throat irritation -Smoking has declined in developed nations Radon causes 21,000 deaths a year in the U.S. -A radioactive gas resulting from natural decay of rock, soil, or water that can seep into buildings -New homes are being built that are radon resistant

49. © 2011 Pearson Education, Inc. Radon risk across the U.S.

50. © 2011 Pearson Education, Inc. Sources of indoor air pollution

51. © 2011 Pearson Education, Inc. Living organisms can pollute indoors Dust mites and animal dander worsen asthma Fungi, mold, mildew, airborne bacteria cause allergies, asthma, other respiratory ailments, and diseases Building-related illness = a sickness produced by indoor pollution Sick building syndrome = a sickness produced by indoor pollution with general and nonspecific symptoms -Reduced by using low-toxicity building materials and good ventilation

52. © 2011 Pearson Education, Inc. We can reduce indoor air pollution In developed countries: -Use low-toxicity materials, limit use of plastics and treated wood, monitor air quality, keep rooms clean -Provide adequate ventilation -Limit exposure to known toxicants -Test homes and offices and use CO detectors In developing countries: -Dry wood before burning -Cook outside -Use less-polluting fuels (natural gas)