"Ambient air" is the outside air that we all breathe. This term is specifically defined by the EPA as "that portion of the atmosphere, external to buildings, to which the general public has access."
In the early 1970s, the EPA listed six major air pollutants that affected the quality of ambient air and established concentration limits for these pollutants. These limits are known as the National Ambient Air Quality Standards (NAAQS). Primary limits or standards were established to protect human health and secondary standards were established to protect human welfare and the quality of life. Through the years, the NAAQS have been revised and amended to account for evolving scientific understanding of air pollution and its impacts. Currently, the six criteria pollutants are:
- Ozone (O3)
- Particulate Matter (PM 2.5 and PM 10)
- Carbon Monoxide (CO)
- Sulfur Dioxide (SO2)
- Nitrogen Dioxide (NO2)
- Lead (Pb)
These six pollutants can cause serious human health problems (including premature mortality) and damage the environment and property. Common sources of these pollutants are coal-fired power plants, industrial manufacturing sources, and on-road and off-road vehicles. The national standards can be viewed online at the National Ambient Air Quality Standards (NAAQS) page. The North Carolina state standards can be viewed online at the N.C. Ambient Air Quality Standards page.
In addition to the criteria pollutants, the N.C. Division of Air Quality (DAQ) monitors a variety of Hazardous Air Pollutants (HAPs). DAQ operates the urban air toxics (UAT) monitoring network in conjunction with the national program (National Air Toxics Trends Station, NATTS), originally proposed and designed by the U.S. EPA in 1999. The UAT monitoring network was started as part of the EPA's effort to address toxic air pollutant emissions in urban areas.
Consumer Air Sensors
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Patrick Butler, P.E.
Ambient Monitoring Chief
Joette Steger, Ph.D.
Projects and Procedures Branch Supervisor
Jim Bowyer, Ph.D.
Laboratory Analysis Branch Supervisor
Electronics and Calibrations Branch Supervisor