Statistical Summary of Ozone Measurements in the National Park System 1992-1997

Miller, Debra

This report summaries air quality monitoring for various sites within the National park Service. The National Park Service (NPS) is required by its Organic Act and the federal Clean Air Act to protect the natural resources of the lands it manages from the adverse effects of air pollution. Of the many gaseous air pollutants that are emitted directly from industrial and mobile sources, or are formed as a result of these emissions, ozone has been found to be one of the most widespread and injurious to human health and vegetation. In order to protect human health and welfare, the U.S. Environmental Protection Agency (EPA) has established, respectively, primary and secondary ozone national ambient air quality standards for maximum allowable ozone concentration levels. These were revised in 1997. The former standards were set at 0.12 ppm (or 120 ppb), averaged over a 1-hour period. In July 1997 the EPA promulgated new standards, both primary and secondary, based upon an 8- hour average value. Under this rule, the annual fourth-highest daily maximum 8-hour ozone concentration, averaged over three years, must not exceed 0.08 ppm (or 80 ppb). This revised rule, however, has been successfully challenged in court, and at present cannot be enforced by EPA.