Question-The EPA has set National Ambient Air Quality Standards (NAAQS) for six (6) principal pollutants, which are called "criteria" air pollutants. These include carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter and sulfur dioxide. Which form of particle pollution, PM 2.5 or PM 10 are included under the rubric of “particulate matter” by the U. S. EPA’s NAAQS?
Answer- Both PM 2.5 and PM 10 are addressed by the NAAQS. Thus, in effect, one may consider there are seven (7), not six(6), “criteria” air pollutants. (https://www.epa.gov/criteria-air-pollutants/naaqs-table; accessed January 2018)