The USEPA has classified six different substances as “criteria pollutants” due to their potential to harm human health and the environment: carbon monoxide, lead, nitrogen dioxide, ozone, sulfur dioxide, and inhalable particulate matter. In order to protect public health, the USEPA has established the National Ambient Air Quality Standards (NAAQS), which set “maximum allowable levels” for each pollutant. The NAAQS are used to determine the status of air quality anywhere in the United States. If levels of the criteria pollutants are determined to be below the maximum allowable levels, the area is said to be in “attainment” status, having attained the standard. If levels rise above allowable amounts, the area is classified as “nonattain- ment” status. Greater Cincinnati is in attainment status for all the criteria pollutants except ozone. On July 17, 1997, the USEPA, based on the latest medical research, proposed to revise the 1-hour ozone NAAQS to an 8-hour standard, and to create a new standard for fine particulate matter smaller than 2.5 microns in diameter. Based on 1999, 2000 and 2001 data, several sites in southwestern Ohio will not meet the new 8-hour standard for ozone. Based on the PM2.5 data collected for 1999, 2000 and 2001 southwestern Ohio will not meet the new fine particulate matter standard…

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