Is the Air Unhealthy to Breathe Today?, June 2001
About 200 real-time, or continuous, air quality monitors for fine particles (PM2.5) have recently been deployed in urban areas in the United States.
There are several different technologies for monitoring real time fine particle concentrations, and no federally specified reference method. Thus results from these monitors are not used to measure compliance with the National Ambient Air Quality Standards (NAAQS). The continuous monitors for fine particles typically measure lower concentrations of fine particles than conventional filter monitors because of the loss of volatile species.
EPA maintains a website that provides links to state and local sources of real-time air quality monitoring data, forecasting, maps, and webcams: http://www.epa.gov/airnow/.
The EPA website was originally developed to provide easy access to ozone data. However, a number of state and local agencies have begun to voluntarily report their PM2.5 data.
For instance, Orlando, Florida, Greensboro, North Carolina, St. Louis, Missouri, and many cities in New Jersey and Washington State have begun providing forecasts of today’s and tomorrow’s particulate matter levels.
Forecasting allows sensitive individuals to take steps such as avoiding outdoor exercise on days when unhealthy air quality is expected.
A regional network of webcams of regional haze in the Northeast may be found at: http://www.hazecam.net/.
Questions to Ask:
- Is my area doing continuous monitoring of fine particle concentrations?
- Does the State intend to make real-time monitoring data available via the internet?
- Is monitoring data made available to the broadcast media?
- Does my area intend to produce forecasts of fine particle concentrations so that the public can take steps to minimize air pollution and stay indoors if necessary?
- Are the real-time monitors reporting consistently lower concentrations than the filter monitors in my area?
- What time of day, and during what season, are fine particle concentrations the highest in my area?
How to Interpret the Monitoring Data
24-hour concentrations of fine particles can be compared to EPA’s Air Quality Index (AQI) level of 40.5 micrograms per cubic meter. This is the level designated as unhealthy for sensitive groups under the AQI public warning program.
The American Lung Association® and health experts generally consider EPA’s 24-hour fine particle National Ambient Air Quality Standard of 65 micrograms per cubic meter to be a very weak standard that is not protective of public health.
For fine particles, the sensitive groups at greatest risk are people with respiratory or heart disease, the elderly and children.
AQI reporting requirements for fine particles took effect in December 1999, in MSA’s that had fine particle monitoring capability, and populations greater than 350,000 people. Continuous monitoring is not required under this program, but a number of states have instituted it voluntarily.
EPA is just now developing the tools to enable areas to provide information that will be most useful to the public. These tools include forecasting models and mapping tools that can predict when high concentrations will occur, to enable people to take protective measures such as staying indoors on days when poor air quality is predicted.
Questions to Ask:
- Do the PM2.5 concentrations reported in my area approach the level of the 24-hour AQI?
- How many days of high 24-hour concentrations are experienced?
- How is my area implementing the AQI public warning program?
