Learn how air pollution can harm your health and the environment, and what EPA is doing to protect the air we breathe.

Ozone can be “good” or “bad” for health and the environment depending on where it’s found in the atmosphere.

National Ambient Air Quality Standards (NAAQS) for ground-level ozone, or ozone pollution, specify a maximum allowed measurement for ozone (O3) to be present in outdoor air.

The Clean Air Act requires EPA to designate areas in the United States after the agency sets a new National Ambient Air Quality Standard (NAAQS) or revises an existing standard

PM stands for particulate matter (also called particle pollution): the term for a mixture of solid particles and liquid droplets found in the air.

CO is a colorless, odorless gas that can be harmful when inhaled in large amounts.

National Ambient Air Quality Standards (NAAQS) for CO specify maximum amounts of carbon monoxide to be present in outdoor air.

How do we know if an area is not meeting CO standards?

Lead is a naturally occurring element found in small amounts in the earth’s crust. While it has some beneficial uses, it can be toxic to humans and animals, causing health effects.

National Ambient Air Quality Standards (NAAQS) for lead (Pb) pollution, specify a maximum amount of lead to be present in outdoor air.

How do we know if an area is not meeting the standards?

EPA’s national ambient air quality standards for SO2 are designed to protect against exposure to the entire group of sulfur oxides (SOx).

National Ambient Air Quality Standards (NAAQS) for SO2 specify maximum amounts of sulfur dioxide to be present in outdoor air.

How do we know if an area is not meeting SO2 standards?

Nitrogen Dioxide (NO2) primarily gets in the air from the burning of fuel. NO2 forms from emissions from cars, trucks and buses, power plants, and off-road equipment.

National Ambient Air Quality Standards (NAAQS) for NO2 specify maximum amounts of NO2 to be present in outdoor air.

How do we know if an area is not meeting NO2 standards?

Hazardous air pollutants are those known to cause cancer and other serious health impacts. 

Learn about pollutants from vehicles and engines that cause harmful health effects and climate change.

Find information about wise driving, choosing fuel efficient vehicles, and other tips for decreasing your carbon footprint.