Humanity and the Weather

Air Pollution

What are the National Ambient Air Quality Standards?

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


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