| A | B |
|---|
| primary | type of pollutants that are put directly into the air by humans or nature |
| natural | type of primary pollutants not produced by humans such as dust, sea salt, volcanic gases and ash, pollen, and swamp gas |
| secondary | type of pollutants that form from chemical reactions |
| smog | formed along with ground level ozone when automobile exhaust reacts with air and sunlight |
| transportation | main source of human-caused pollution |
| industrial | type of air pollution caused when factories or power plants burn fossil fuels |
| indoor | type of air pollution found inside a building |
| household cleaners | something that causes indoor air pollution |
| winds | can move pollution from one place to another |
| acid precipitation | rain or snow that can kill living things because it contains acids from air pollution |
| ultraviolet | more of these rays reach the Earth’s surface through the growing ozone hole |
| health | Daily exposure to small amounts of air pollution can cause serious ______ problems. |
| Environmental Protection Agency | a government organization charged with protecting human health and safeguarding the natural environment |
| Clean Air Act | law signed in 1970 that gives the EPA the authority to check air quality and control standards |
