PM10 Background
PM10 is particulate matter equal to or less than 10 micrometers in aerodynamic diameter. In January 1988 the first PM10 monitor was installed in Virginia. This was the beginning of the Virginia Ambient Air Monitoring Network sampling for inhalable particulate. Over the years, there have been dozens of PM10 monitoring sites around the state. However, because the new PM2.5 monitors were being introduced and started up in 1999, the PM10 monitoring network was dramatically reduced to free up manpower required for the new samplers. There are currently thirteen PM10 monitoring sites in Virginia.
PM2.5 Background
In 1997, the U.S. Environmental Protection Agency promulgated new national ambient air quality standards for PM2.5 (particle matter equal to or less than 2.5 microns in aerodynamic diameter). EPA determined that these standards are necessary to protect public health and the environment.
24-Hour Mass Samplers
The PM2.5 monitoring network began at the end of January 1999. The PM2.5 sequential samplers collect a 24-hour sample on a stretched Teflon filter. Most samplers in Virginia collect a sample every third day, however, there are four monitoring sites across Virginia where the samplers operate every day. PM2.5 sequential samplers used in Virginia are manufactured by Thermo Fisher Scientific.
Continuous Mass Monitors
There are currently seven continuous PM2.5 mass monitors in the Virginia air monitoring network. Fairfax County Health Department operates one at the Mason Governmental Center on Columbia Pike. The National Park Service operates one for VA DEQ at their air quality monitoring station at Big Meadows. The VA DEQ operates continuous PM2.5 monitors at five sites: Math & Science Center in Henrico County, VA School in Hampton, at Round Hill Montessori Elementary School in Roanoke, at the air monitoring site in Rest, VA (just above Winchester), and at the Albemarle High School site just outside Charlottesville. All seven monitors are Thermo Fisher Scientific TEOMs (Tapered Element Oscillating Microbalance). Data is captured as one-hour averages.
24-Hour Speciation
At the present, there is only one PM2.5 Speciation Sampler operating in Virginia, and is at the Math & Science Center in Henrico County. It is classified as a National Mini-Trends site, and operates on a one-in-three day sampling schedule. Fine particulate matter is collected on nylon, Teflon, and quartz filters, in three modules. These modules are picked up by the operator, after the 24-hour sampling period, and shipped refrigerated to RTI, the EPA contract lab in North Carolina. The lab will analyze the filter for: mass loading, trace elements (such as: aluminum, antimony, arsenic, barium, bromine, zirconium), cations (ammonium, potassium, sodium), anions (nitrate, sulfate), and carbons (carbonate carbon, elemental carbon, organic carbon, total carbon).
These samples give a "chemical fingerprint" of air masses moving through the Richmond area. This data, in conjunction with past data from the former Virginia speciation sites, and data from other states give a representative picture of the constituents of the air samples, which help identify sources of high values, and show how the air masses move over a broad area.
Virginia's PM2.5 Network
The current PM2.5 Monitoring Network for Virginia has been developed following the requirements of 40 CFR Part 58 and applying EPA's "Guidance for Network Design and Optimum Site Exposure for PM2.5 and PM10". Please send your comments or questions to Tom Jennings at tfjennings@deq.virginia.gov.
PM2.5 Annual Summary Data
PM2.5 Summary Data
Please send your comments or questions to Tom Jennings at tfjennings@deq.virginia.gov.