- The atmosphere -

1. - The atmosphere -

2. The atmosphere’s composition

3. The atmosphere’s four layers • Atmospheric layers have different • Temperatures • Densities • Composition

4. The troposphere drives weather and climate • Wind, temperature, pressure, humidity, cloudiness • Weather=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

5. Thermal (temperature) inversion & pollution • Air temperature decreases as you go up (troposhpere) • But warm air rises, causing vertical mixing • Thermal inversion = a layer of cool air beneath warm air • Denser, cooler air at the bottom of the layer resists mixing • Air doesn’t mix, it sits • Inversions trap pollutants in cities surrounded by mountains

6. 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 better technology • Developing countries and urban areas still have big problems

7. 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 (clouds) • Reflect sunlight • Cool the atmosphere and surface Mount Saint Helens eruption in 1980

8. Natural sources pollute: fires • Fires pollute the atmosphere with soot (particulate) 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

9. Natural sources pollute: dust storms • Wind over arid land sends huge amounts of dust aloft • Even across oceans • Worsened by irresponsible farming and grazing: • Erosion • Desertification

10. We create outdoor air pollution too • Point sources= specific spots where large quantities of pollutants are discharged (power plants and factories) • Non-point sources= more diffuse, often consisting of many small sources (like cars) • 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

11. Pollutants exert local and global effects • Residence time = how long a pollutant stays in the atmosphere • Pollutants with short residence times act locally • Particulate matter, car exhaust • Pollutants with long residence times act regionally or even globally • Pollutants causing climate change or ozone depletion

12. Pollutants: CO and SO2 • Carbon monoxide(CO)= colorless, odorless gas • Produced mostly by incomplete combustion of fuel • From engines, industry, burning garbage, residential wood burning • Dangerous even in small concentrations • Sulfur dioxide (SO2) = colorless gas with a strong odor • Coal emissions from electricity generation & industry • Harmful in the long term and forms acid rain

13. Pollutants: NO2 • Nitrogen oxides (NOx) = formed when nitrogen and oxygen react at high temperatures in engines • Vehicles, industrial combustion, electrical utilities • Contribute to smog and acid precipitation • Nitrogen dioxide (NO2)=a highly reactive, foul-smelling reddish brown gas • Perhaps the most common nitrogen oxide • Causes respiratory damage in long term • (Pulmonary edema in acute exposure)

14. Pollutants: ozone • Tropospheric ozone (O3) = a colorless gas with a strong odor • From interactions of sunlight, heat, nitrogen oxides, and volatile carbon-containing chemicals • A secondary pollutant • A major component of smog • Harms tissues and causes respiratory problems • Biggest breaker of EPA guidelines

15. Pollutants: particulate matter and lead • Particulate matter = solid or liquid particles • Primary pollutants: dust and soot • Secondary pollutants: sulfates and nitrates • Damages respiratory tissue when inhaled • Lead = in gasoline and industrial metal smelting • Accumulates and damages the nervous system • Banned in gasoline in developed countries

16. 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 CO2/yr as well as other pollutants!

17. 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, acid rain, stratospheric ozone depletion

18. The EPA sets standards • The EPA sets nationwide standards for emissions and concentrations of toxic pollutants • States monitor air quality • The EPA takes over enforcement if state 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

19. Areas in the U.S. failing air quality standards National Ambient Air Quality Standard

20. 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

21. 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 • Include heavy metals, VOCs, diesel fumes, smog ...

22. U.S. health risks vary geographically Non-cancerous respiratory ailments from air pollution Nationwide cancer risks from air pollution alone

23. Industrializing nations suffer increasing pollution • Outdoor pollution is getting worse • Factories and power plants pollute • Governments emphasize economic growth, not pollution control • People burn wood and charcoal and are buying cars • China has the world’s worst air pollution • Coal burning, more cars, power plants, factories • Causing over 300,000 premature deaths/year

24. Pollution. Smog in Beijing surrounds an Olympic stadium More people own cars

25. (Air pollution in China) • The government is trying to decrease pollution • Shutting down heavily polluting factories and mines • 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 • Doing very bad things – check wikipedia...

26. Smog: our most common air quality problem • Smog = an unhealthy mixture of air pollutants over urban areas • Industrial (gray air) smog = industries burn coal or oil • Sulfur dioxide reacts with atmosphere to produce sulfuric acid • Coal-burning industrializing countries face health risks • Coal and lax pollution control Smog in Donora killed 21 people and sickened 6,000

27. Photochemical (brown air) smog • Formed in hot, sunny cities surrounded by mountains • Light causes primary pollutants and atmospheric compounds to react • Morning traffic releases NO and VOCs • Irritates eyes, noses, and throats • Los Angeles smog kills 3,900 and costs $28 billion/year High levels of NO2 cause photochemical smog to form a brown haze over cities

28. Stratospheric ozone depletion • Ozone layer = ozone in the lower stratosphere • Blocks incoming ultraviolet (UV) radiation • Ozone-depleting substances= human-made chemicals that destroy ozone • Halocarbons • Chlorofluorocarbons (CFCs) = a halocarbon used as refrigerants, in fire extinguishers, in aerosol cans, etc. • Releases chlorine atoms that split ozone

29. The Antarctic ozone hole • Super-cold atmosphere in winter break CFCs down more quickly into ozone-destroying chlorine • A polar vortex (swirling winds) traps the chlorine • The chlorine destroys the ozone • December’s warmer air shuts down the polar vortex • Atmosphere mixes

30. The Montreal Protocol • Montreal Protocol (1987) = 196 nations agreed to cut CFC production in half by 1998 • Follow-up agreements deepened cuts, advanced timetables, and addressed other ozone-depleting chemicals • Considered our biggest environmental success story • Research developed rapidly, along with technology • Policymakers included industry in helping solve the problem

31. Protecting the ozone layer International agreements reduced ozone-depleting substances The hole in the ozone has stopped growing

32. 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

33. Impacts of acid deposition • Nutrients are leached from topsoil • Metal ions (aluminum, zinc, etc.) are converted into soluble forms that pollute water • Affects surface water and kills fish • Damages crops • Erodes stone buildings, corrodes cars, erases writing on tombstones

34. pH (acidity) of precipitation in the U.S. • The acid-neutralizing capacity of soil, rock, or water impacts the severity of acid rain’s effects Many regions of acidification are downwind of major sources of pollution

35. 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 • 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

36. Indoor airpollution Indoor air pollution=in any building 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 fully tested Low air flow means pollutants build up!

37. Indoor air pollution in the developing world From burning wood, charcoal, dung, crop wastes with poor ventilation Fuel burning pollution causes 1.6 million deaths/year Soot and carbon monoxide Pneumonia, bronchitis, lung cancer, allergies, cataracts, asthma, heart disease, etc.

38. Tobacco smoke and radon Common indoor pollutants in developed nations! Secondhand smoke from cigarettes is very dangerous Contains over 4,000 chemical compounds Causes eye, nose, and throat irritation Radon causes 21,000 deaths a year in the U.S. (lung cancer) A radioactive gas resulting from natural decay of rock, soil, or water that can seep into buildings

39. Radon risk across the U.S.

40. VOCs pollute indoor air The most diverse group of indoor air pollutants Released by everything from plastics and oils to perfumes and paints Health effects: Eye, nose, and throat irritation; headaches, loss of coordination, nausea; damage to liver, kidney, and central nervous system. Some organics can cause cancer in lab animals; some are suspected or known to cause cancer in humans. Key signs or symptoms associated with exposure to VOCs include conjunctival irritation, nose and throat discomfort, headache, allergic skin reaction, dyspnea, declines in serum cholinesterase levels, nausea, emesis, epistaxis, fatigue, dizziness. Formaldehyde leaking from pressed wood and insulation irritates mucous membranes and induces skin allergies Pesticides seep through floors and walls

41. Sources of indoor air pollution

42. 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 Sick building syndrome = a sickness produced by indoor pollution with general and nonspecific symptoms Reduced by using low-toxicity building materials and good ventilation

43. 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 Ventilation! Use less toxic products In developing countries: Dry wood before burning More efficient stoves Ventilation! Use less-polluting fuels (natural gas)