• Criteria Pollutant are 1970 amendments to the Clean Air Act requiring the Environmental Protection Agency (EPA) to establish national ambient air quality standards (NAAQS) for certain pollutants known to be hazardous to human health. The Environmental Protection Agency has defined and set standards to protect human health and well-being for six pollutants: ozone, carbon monoxide, total suspended particles, sulfur dioxide, lead, and nitrogen oxide. The term “criteria pollutants” comes from the requirement that the Environmental Protection Agency describe the characteristics and potential impacts of these pollutants on health and well-being. It is on the basis of these criteria that standards are set or revised.