DEQ maintains a network of air monitors across the state. Some monitors measure common, or criteria pollutants such as ozone, nitrogen dioxide (NO2), particulate matter (PM2.5 and PM10), carbon monoxide (CO), sulfur dioxide (SO2), as well as lead and toxic metals. 

Monitors may be sited due to a number of considerations including regulatory requirements, and their intended purpose. Some monitors, such as toxic metals monitors or near road monitors, may be placed in close proximity to known or suspected pollution sources, whereas other monitors (often criteria pollutant monitors) are placed further away from distinct pollution sources such as factories or busy roads so that ambient air pollution levels can be measured. Additional monitors are placed along roads in Northern Virginia as part of the RAPIDPASS program to measure emissions from vehicles.

DEQ's air monitors, along with information gathered on emissions trends, are used to plan programs to further improve air quality, as well as to measure the success of existing programs that limit air pollution.

DEQ air monitoring locations

Criteria pollutants
Air toxics
Photochemical assessments