Air Pollution

2. a mixture of secondary pollutants formed on sunny days from nitrogen oxides and volatile organic compounds
4. the lowest atmospheric layer where weather and living organisms exist
6. the atmospheric layer containing the ozone layer that blocks ultraviolet radiation
8. pollutants released directly into the air from a source
11. carbon based liquids that easily evaporate and contribute to ozone and smog formation
16. an international agreement to reduce use of chemicals that damage the ozone layer
18. pollutants formed when primary pollutants react in the atmosphere
19. a law passed in 1970 to regulate air pollution and limit harmful emissions
20. a gas from burning coal that can form sulfuric acid and irritate the respiratory system

1. the atmospheric layer where meteors burn up
3. a condition where warm air traps cooler air below causing pollution to build up
5. the layers of gases surrounding Earth
7. a device in vehicles that reduces harmful emissions by converting gases into less harmful substances
9. a colorless odorless gas produced by fuel burning that blocks oxygen in the blood
10. a harmful secondary pollutant formed from nitrogen oxides and volatile organic compounds
12. precipitation with a low pH caused by sulfuric and nitric acids
13. tiny particles like dust smoke and soot that can enter the respiratory system
14. the upper atmospheric layer that absorbs high energy radiation from the sun
15. a toxic metal pollutant that can damage the nervous system
17. reddish brown gases from vehicles and soil bacteria that form smog ozone and nitric acid