Air

1. Air Section #1: What Causes Air Pollution

2. when harmful substances build up in the air to unhealthy levels these harmful substances can be in the form of a solid, liquid, or gas most pollution is from human activities, but some comes from natural sources Air Pollution

3. volcanoes – spew clouds of particles (ash) & gases (sulfur dioxide) dust (think about the dust kicked up from plowing a field) pollen & spores (growing season) salt from sea spray Natural Sources of Air Pollution

4. pollutant that is put directly into the air by a human activity Example = soot from smoke (burning wood, industries, vehicles, etc.) main sources of primary pollutants = electricity, industry, & transportation Primary Pollutants

5. Sources of Primary Pollution in the U.S. per day

6. carbon monoxide nitrogen oxide sulfur dioxide chemicals called VOCs (volatile organic compounds) particulate matter (PM) Other Primary Air Pollutants

7. vehicle exhaust emissions coal-burning power plants refineries metal smelters burning fuels mining operations incinerators wood-burning fireplaces fields & roads Sources of Air Pollutants

8. VOCs from a Refinery

9. when a primary pollutant comes in contact with other primary pollutants or with naturally occurring substances (like H2O vapor) and a chemical reaction takes place Secondary Pollutants

10. an example of a secondary pollutant is ground level ozone that forms when car & truck emissions react with the UV rays of the sun & then mix with O2 in the atmosphere Secondary Pollutants

11. not a new phenomenon – occurs whenever something is burned there are records from 2000 years ago from a Roman philosopher complaining about the foul air in Rome in 1273, England’s King Edward I ordered the hanging of a citizen for disobeying the “clean air act” when he illegally burned a very dirty kind of coal called sea-coal History of Air Pollution

12. almost 1/3 of our air pollution comes from gasoline burned by vehicles the EPA started regulating emissions in 1980 required the gradual elimination of lead from gasoline & the addition of catalytic converters to tailpipes to clean exhaust gases of pollutants Motor Vehicle Emissions

13. Catalytic Converter

14. car seats can be covered in a plastic that contains a VOC called vinyl chloride steel smelters send 1000s of metric tons of SO2 into the atmosphere to produce the body & frame VOCs escape into the atmosphere whenever you fill the tank with gasoline A Car’s Contribution of Air Pollution

15. exhaust is a major source of nitrogen oxides, carbon monoxide, & hydrocarbons in some developing countries, exhaust can also contain poisonous substances each car releases 4.5 metric tons of CO2 each year A Car’s Contribution of Air Pollution

16. established in 1990 vehicles that have no tailpipe emissions, no emissions from gasoline, & no emissions from control systems by 2016, 16% of all vehicles (including SUVs, trucks, etc.) must be zero-emission vehicles California - Zero Emission Program

17. include electric cars & vehicles with advanced battery power vehicles powered by hydrogen fuel also includes partial zero-emission vehicles like hybrid-electric cars & cars with methanol fuel cells programs have been adopted by Maine, Massachusetts, New York, & Vermont Zero-Emission Vehicles

18. industries & power plants burn fossil fuels to get the energy they need this releases huge quantities of SO2 & NO into the air they also produce VOCs that form toxic fumes Industrial Air Pollution

19. oil refineries chemical manufacturing plants furniture refinishers automobile repair shops dry cleaners Industries Producing VOCs

20. VOC Emissions from Dry Cleaning

21. Clean Air Act requires many industries to use scrubbers or other pollution-control devices scrubbers remove some of the more harmful substances electrostatic precipitators are machines used in cement factories & coal-burning power plants to remove dust particles from smokestacks Regulating Industrial Pollution

22. The scrubber machine moves gases through a spray of water that dissolves many pollutants like ammonia

23. gas containing dust particles is blown through a chamber containing an electrical current an electrical charge is transferred to the dust particles, causing them to stick to each other & the sides of the chamber Electrostatic Precipitators

24. when air pollution hangs over urban areas & reduces visibility results from chemical reactions that involve sunlight, air, automobile exhaust, & ozone affected cities include, LA, Denver, & Phoenix Smog

25. How Smog Forms over Major Cities

26. air circulation usually keeps air pollution from reaching dangerous levels in the atmosphere as the suns warms the earth and the warm air rises up, it carries pollutants away from the ground sometimes though, pollution is trapped close to the surface with a temperature inversion Temperature Inversions

27. during an inversion, the temperatures of the air above are warmer than the air below this keeps the cooler air at the surface from moving upwards, thus trapping pollutants with the cooler air below chances increase when a city is in a valley & surrounded by mountains Temperature Inversions

28. Major Sources ofGroundwater Pollution