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1998 News Releases


Note To Weathercasters

Release Date: 12/07/1998
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(#98165) New York, N.Y. -- Attached is a press advisory that was issued by the U.S. Environmental Protection Agency (EPA) in Washington, D.C. on Friday, December 4. The advisory is regarding an update of EPA's Pollution Standards Index, which is used by area weathercasters to predict poor air quality days and to communicate about health effects associated with certain pollution levels.

Ground-level ozone, or smog, remains a serious air pollution problem in the entire tri-state area and some areas of upstate New York. In July 1997, the EPA revised federal air pollution standards for ground-level ozone because health studies showed that it can be more harmful than originally thought. Specifically, the studies showed that ground-level ozone can cause adverse health effects in individuals who are exposed over a long period of time (8 hours) to ozone concentrations lower than the previous EPA standard. EPA used this information to set tougher new ground-level ozone standards that are more protective of human health.



Dave Ryan 202-260-2981

In an action which will help local TV and radio weather casters better inform citizens about upcoming good or bad air quality days, EPA today announced a proposal to revise the Agency's Pollutant Standards Index (PSI), also known as the Air Quality Index, to enhance the public's right-to-know about daily air pollution levels in their local communities. The PSI provides EPA with a uniform system of measuring pollution levels for the major air pollutants regulated under the Clean Air Act. State and local officials use the PSI as a public information tool to advise the public about the general health effects associated with different pollution levels, and to describe what precautionary steps may be appropriate if levels rise into the unhealthy range. States monitor the daily levels of five pollutants for which EPA has established national ambient air quality standards: ground-level ozone (smog), particulate matter, sulfur dioxide, carbon monoxide and nitrogen dioxide.

The proposal would also provide information for a new national Internet website that includes more timely air quality data, along with forecasts of summertime smog levels in many states (website: Under the Clean Air Act, EPA was required to establish a nationally uniform air quality index for the reporting of air quality, and in 1976 the Agency established the PSI to help state and local government agencies provide citizens with accurate, timely and easily understandable information on protecting their health.

These five pollutants all have separate numerical health-protection standards, so to avoid confusion, state and local agencies use the index to convert their monitored levels to one number on a uniform scale ranging from 0 (good) to 500 (hazardous) and report this number to the public. Today's proposal would add an additional air quality category just above the level of the health standard 100. Currently, PSI values from 101 - 200 are characterized as "unhealthful"; the change would establish a new category from 101 - 150 characterized as "unhealthy for sensitive groups" (such as asthmatics) and a category of 151 - 200 as "unhealthy". To the extent that state and local agencies use color maps or charts to communicate PSI values to the public, this proposal would require uniform colors associated with each PSI category. For instance, the "unhealthy" category would be represented by the color red. Today's proposal will appear soon in the Federal Register with a 45-day public comment period, but can be read immediately on the Internet under "Recent Actions" at website: For further technical information, phone Susan Stone at 919-541-1146 (e-mail: or Terence Fitz-Simons at 919-541-0889 (e-mail: of EPA's Office of Air Quality Planning and Standards.

For more information contact:
Mary Mears, Press Office
EPA Region 2
290 Broadway
NY, NY 10007-1866
Voice: 212-637-3669 FAX: 212-637-5046 E-Mail: