Fine Particle Filter Monitors Measure Air Quality, June 2001
There is an important new source of localized information that can serve as an indicator of environmental health trends in your region.
Recent research implicates fine particle air pollution in tens of thousands of premature deaths, hospitalizations, and emergency room visits each year in the U.S. from cardiovascular and respiratory causes.
To prevent these effects, the U.S. Environmental Protection Agency (EPA) established new National Ambient Air Quality Standards (NAAQS) for fine particles (PM2.5, particles less than 2.5 microns in diameter) in July 1997.
With the establishment of the PM2.5 air quality standards, EPA and the States commenced a new monitoring program to assess fine particle concentrations in metropolitan areas nationwide.
The initial monitoring data are now available, so that the public can begin to determine whether fine particle concentrations in their area may be of health concern.
It will be another year before enough data has been gathered for EPA to ascertain which areas will violate the standards and must develop clean up plans to reduce fine particle levels.
Where to Get the Monitoring Information
Approximately 1,100 filter monitors have now been deployed in urban areas across the country.
The easiest way to access the monitoring data is in summary form, from an analysis prepared by EPA. An analysis of the 1999 data, the first year that widespread monitoring took place, was published by EPA on their website.
Two maps and a summary table containing the data underlying the maps are available at:
http://www.epa.gov/oar/oaqps/pm25/docs.html
Data for the 1999 calendar year are incomplete in many areas. For instance, data for a couple of states, Massachusetts and New Hampshire, are missing from the map, because the states placed “red flags” on all their monitoring data due to equipment problems. Other states, such as Alabama, only reported data for the first quarter of 1999. EPA excluded more than one-third of the data from South Dakota, Tennessee, and Mississippi because of questions about data validity.
Because fine particle concentrations are typically higher during the summer in the East, and during the winter in the West, incomplete data can give an inaccurate picture of annual average or peak 24-hour concentrations.
In addition, raw data for the year 2000 are also available from EPA’s Aerometric Information Retrieval System (AIRS) database. A subset of the AIRS data for fine particles is now searchable online at: http://www.epa.gov/air/data/.
Fine particle monitoring data may also be available directly from the states.
State contacts for this data are listed at: http://www.epa.gov/ttn/airs/airscont/airscont.pdf.
The California Air Resources Board publishes an annual Almanac of Emissions & Air Quality. The 2001 edition contains information on the peak 1999 24-hour PM 2.5 concentrations at monitors throughout the state.
Some states maintain websites where air quality data can be obtained.
New York: http://www.dec.state.ny.us/website/dar/baqs/pm25mon.html
Washington: http://airr.ecy.wa.gov/Public/aqn.html
Texas: http://www.tnrcc.state.tx.us/cgi-bin/monops/psi_rpt
Missouri: http://www.dnr.state.mo.us/deq/esp/aqm/pm25site.htm
Virginia: http://www.deq.state.va.us/airmon/pm25data.html
Iowa: http://www.uhl.uiowa.edu/Services/AirQuality/f_realtime.html
Pima County, Arizona: http://www.deq.co.pima.az.us/empact/PM25/PM25_data.htm
Triad, NC: http://www.co.forsyth.nc.us/EnvAffairs/DlyAirQualRpt.htm
EPA guidelines allow monitors to be sited away from areas where the highest concentrations are expected, such as near industrial sources of combustion, highways, or bus depots. Thus the data reported may not reflect levels at places where the risks to health are the greatest.
How to Interpret the Monitoring Data
We suggest that annual average concentrations be compared with the annual average fine particle NAAQS of 15 µg/m3, for an indication of unhealthful air quality. Please note that violations of the NAAQS are determined based on 3 full years of monitoring information.
In 1999, annual average concentrations recorded at individual monitoring stations ranged from 5.84 µg/m3 in Hancock County Maine, to 30 µg/m3 in Riverside-San Bernardino, California, for sites where data were reasonably complete, that is, all four quarters of 1999 had data which was 75 percent complete.
The American Lung Association® and health experts generally consider EPA’s 24-hour fine particle NAAQS of 65 µg/m3 to be a very weak standard that is not protective of public health. Therefore, we recommend that 24-hour concentrations be compared to the lower level of 40.5 µg/m3 designated as unhealthy for sensitive groups in EPA’s public warning program known as the Air Quality Index (AQI).
For fine particles, the sensitive groups at greatest risk are people with respiratory or heart disease, the elderly and children.
In 1999, the 98th percentile 24-hour concentrations recorded at individual monitoring stations ranged from 12 µg/m3 in the Providence-Fall River-Warwick, RI-MA Metropolitan Statistical Area, to 92 µg/m3 in Merced, California, for sites where data were reasonably complete, that is, all four quarters of 1999 had data which was 75 percent complete.
Questions to Ask
- Is the monitoring data for my area complete? What difficulties led to non-reporting or partial reporting of data in 1999?
- Have those difficulties been resolved?
- Is monitoring data collected on a daily basis in my area?
- What are the major sources of fine particle pollution in my area, based on speciation of the monitoring data?
- Are the monitors located in areas of maximum expected concentrations?
- Do the PM2.5 concentrations reported in my area approach the level of the annual average standard, or the level of the 24-hour AQI?
- How many days of high 24-hour concentrations are experienced?
