REVISIONS TO EPA'S OZONE AIR QUALITY INDEX FACT SHEET ACTION • On March 12, 2008 EPA revised its Air Quality Index (AQI) for ozone to reflect changes to the national ambient air quality standards for ground-level ozone. The AQI is EPA's color-coded tool for communicating daily air quality to the public. • The AQI revisions address the ranges of ozone that are represented by the AQI categories, such as "good," "moderate," "unhealthy for sensitive groups," and "unhealthy." EPA has adjusted the upper end of the "moderate" range to be equal to the new primary 8-hour ozone standard, which is 0.075 parts per million (ppm), and has made proportional changes to the other categories. This action is part of the rule EPA issued to significantly strengthen the ozone standards. • Under the revised AQI, ozone levels above 0.075 ppm would be considered in the "unhealthy for sensitive groups" category -known to many people as a "code orange" air quality day. When ozone is in this category, EPA recommends certain groups adjust their activity levels to reduce their ozone exposure. These groups include children and adults who are active outdoors, people with asthma or other lung diseases and older adults. • State and local governments may begin using the new AQI breakpoints immediately to issue voluntary ozone forecasts and for calling air quality action days. Cities of 350,000 and larger are required to report the daily AQI and must begin using the new breakpoints no later than 60 days after the revised ozone standards are published in the Federal Register. • The table below shows the new breakpoints: 1997 2008 Category ^ 8-hour 8-hour (ppm) (ppm) Good 0-50 0.000-0.064 0.000-0.059 Moderate 51-100 0.065-0.084 0.060-0.075 Unhealthy for Sensitive Groups 101-150 0.085-0.104 0.076-0.095 Unhealthy 151-200 0.105-0.124 0.096-0.115 Very Unhealthy 201-300 0.125-0.374 0.116-0.374 301-400 No Change No Change Hazardous 401-500 No Change No Change ------- BACKGROUND: • EPA calculates the AQI for five major air pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution (also known as particulate matter), carbon monoxide, sulfur dioxide, and nitrogen dioxide. An AQI value of 100 generally corresponds to the "primary," national air quality standard for the pollutant, which is the standard EPA sets to protect public health. • AQI values below 100 are generally thought of as satisfactory. When AQI values are above 100, air quality is considered to be unhealthy — at first for certain sensitive groups of people, then for everyone as AQI values get higher. • People can reduce their exposure to ozone by changing the time of their activity or simply taking it easier on days when ozone levels are expected to be high. For example, a runner could run in the morning, when ozone levels are lower, instead of in the afternoon, when conditions tend to be more favorable for ozone formation. A runner also could reduce exposure by taking a walk instead of going for the run. • State and local governments issue voluntary ozone forecasts for more than 300 U.S. cities during the ozone season, which generally runs from May 1 to September 30. More than 200 cities also issue forecasts for particle pollution, which can be a problem year-round, depending on location. These forecasts are widely carried on television and in newspapers, and also are available on the AIRNow Web site, at www.airnow.gov. FOR MORE INFORMATION • For a daily map showing air quality forecasts across the country, got to www.airnow.gov and click on "National Forecast." • To learn more about air pollution and health, go to www.airnow.gov and click on "Publications." • For more information about EPA's action to strengthen the national ozone standards, visit www.epa.gov/groundlevelozone. ------- |