Program of the Month
DEQ and Shenandoah National Park workers check the particulate monitor located in the park.
Air Monitoring: From Tupperware® to state-of-the-art
Monitoring the air we breathe has come a long way since the 1960s when scientists set Tupperware® containers outside to capture pollutants, collected a month at a time and reported in tons per square mile.
“In the late 60s we put a man on the moon, but we were still using an antiquated system to monitor air pollution,” said Tom Jennings, an air monitoring engineer at the Department of Environmental Quality’s Office of Air Quality Monitoring. “It has changed dramatically.”
Now there is a specialized instrument for each pollutant measured, and instead of visiting each site to collect measurement information, DEQ staff connects to some monitoring locations remotely via the telephone.
Better technology means scientists have a better idea of what is in the air, and the good news is that overall air quality is improving.
“There has been a tremendous increase in the quality of air Virginians breathe over the last 30 years,” Jennings said.
The work done by DEQ’s air monitoring program forms the foundation of what is known about Virginia’s air quality. By monitoring pollutants in the air over time, scientists can determine air quality trends, and identifying how they change can determine if air quality is improving or not.
DEQ’s seven regional offices operate air monitoring instruments at about 50 locations around the state. The central and regional DEQ staffs work with Fairfax County, the city of Alexandria, the U.S. National Park Service and the U.S. Forest Service in a cooperative air monitoring effort for Virginia. The DEQ Office of Air Quality Monitoring also works with DEQ’s air analysis group that uses monitoring data to make forecasts and predictions of air quality.
DEQ monitors toxic air pollutants and criteria pollutants such as ozone and particulate matter. The air monitoring group compiles and validates the data collected from the monitoring sites and sends the information to the U.S. Environmental Protection Agency in compliance with the U.S. Clean Air Act.
The effort to monitor toxic air pollutants is the newest addition to the program. Toxic air pollutants measured by DEQ include metals, compounds that react with sunlight to produce ozone pollution and carbon-based chemicals. Monitors using filters, canisters and cartridges pull air in and collect toxins for 24 hours every few days at locations in Fairfax County, Norfolk and Richmond. DEQ collects the canisters and sends them to the Virginia Division of Consolidated Laboratory Services for analysis.
DEQ will soon have a new instrument, called a open path Fourier transfer infrared spectrometer, to identify and measure toxic pollutants. The instrument will be useful for incidents such as tire fires or chemical spills and will give immediate results.
A DEQ staff member repairs an ozone analyzer.
This group is also responsible for conducting special air quality studies at the requests of citizens.
While toxic air pollutants are present in the atmosphere, they are found in much smaller quantities than criteria pollutants, which include ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide and particulate matter. Criteria pollutants are pollutants that the EPA has identified as potentially affecting human health and set air quality standards that limit their amount. DEQ monitors one or more of these criteria pollutants continuously at 31 locations in Virginia and extracts the data remotely via the telephone line.
Unlike the other criteria pollutants, particulate matter is monitored around the state using a combination of continuous and intermittent samplers. While continuous monitors measure particulate concentrations everyday, intermittent samples take in air and collect particles on filters for 24 hours every three days or every six days. DEQ staff collects the filters and sends them to the Virginia Division of Consolidated Laboratory Services.
DEQ measures two sizes of particulate matter: small, visible particles (10 microns in diameter, called PM 10) and very fine particles (2.5 microns in diameter, called PM 2.5) that are smaller than the width of a human hair.
Small particles of dust, soot and smoke from automobile and industrial emissions, fires and other sources make up particle pollution. Emissions from automobiles and industries also act as sources of carbon monoxide, sulfur dioxide, nitrogen oxides and compounds involved in ozone formation.
The EPA has established regulations that set allowable levels (or standards) of each criteria pollutant based on the potential to affect human health. If measurements do not exceed the allowable levels, then U.S. air quality standards have been met.
“We are now measuring air quality in Virginia that meets federal air quality standards for all pollutants, except for ozone in some urban areas ,” Jim Sydnor, director of the DEQ air quality and monitoring program, said.
Additional information on air monitoring information in Virginia is available on the DEQ web site and the U.S. Environmental Protection Agency's web site.