Part of the Clean Air Act, the National Ambient Air Quality Standards (NAAQS) are set values that are considered the maximum limits before air becomes too unhealthy to breathe safely. Industries that produce pollutants must adhere to these standards or else face fines and other penalties from the federal government. The standards are listed below.
National Ambient Air Quality Standards
| Pollutant |
Concentration |
Over an Average Period |
| Carbon monoxide |
9 parts per million |
8 hours |
|
35 parts per million |
1 hour |
| Lead |
1.5 micrograms per cubic meter |
3 months |
| Nitrogen dioxide |
100 micrograms per cubic meter |
12 months |
| Ozone |
120 parts per billion |
hourly average can’t exceed once per year over three years |
| Particulate matter |
50 micrograms per cubic meter |
12 months |
|
150 micrograms per cubic meter |
24 hours |
| Sulfur dioxide |
80 micrograms per cubic meter |
12 months |
|
365 micrograms per cubic meter |
24 hours |
