criteria pollutants

Criteria pollutants are a set of common air pollutants that the U.S. Environmental Protection Agency (EPA) monitors because they can harm human health, damage the environment, and affect visibility. These pollutants include ground-level ozone (smog), particulate matter (tiny particles from dust, dirt, and smoke), carbon monoxide (a poisonous gas from vehicles), sulfur dioxide (from burning fossil fuels, causing acid rain), nitrogen dioxide (from vehicle exhaust and industry), and lead (a toxic metal from old paint and industrial processes). Regulations target these pollutants to reduce health risks and protect air quality.