Performance Measures

Overview

The National Park Service (NPS) measures the success of its air resource management program based on results achieved. Monitoring data show that air pollution is affecting some park resources - like visibility - nationwide. Therefore, consistent with the Government Performance and Results Act, the NPS has established an air quality goal: By September 30, 2008, air quality in 70% of reporting park areas has remained stable or improved.

The NPS Air Resources Division oversees the air resource management program. We think it is important to measure the program's effectiveness based on outcomes even though the NPS has no authority to regulate sources of air pollution located outside park boundaries. We believe we can make a difference by: (1) acquiring high quality data, (2) making that information available to the general public, and (3) identifying and seizing opportunities to participate in decisions being made by regulatory agencies that might affect air quality in parks.

We use several indicators to measure progress. One indicator looks at visibility trends on the best and worst visibility days. Another tracks changes in ozone concentrations based on the 3-year average of the annual fourth highest daily maximum 8-hour concentration. The final indicator focuses on acid deposition, specifically changes in wet deposition of sulfate, nitrate, and ammonium ions. An area meets the goal if it does not show statistically significant deterioration in any of the performance indicators during the most recent 10-year period for which data is available.

For the latest analysis for the years 1996-2005, the NPS expanded its reporting to include not only parks with on-site air quality monitoring, but also parks with nearby monitoring. This increased the number of reporting parks from 52 to 141. Of these, 86% met the goal.

The map below shows the national parks with monitoring analyzed in the report. As an example, the zoomed in graphic presents results of the 1996-2005 trends for all indicators for Rocky Mountain National Park. The darker blue and red boxes represent statistically significant improving or degrading trends during 1996-2005. The light red box represents a degrading trend that is not statistically significant at the 0.05 level but would be at the 0.15 level. The gray boxes represent no trend.

Graphics for parks in the East (p. 22) and the West (p. 23) illustrate the monitoring results over entire regions. These graphics, as well as comprehensive air quality information, are available in the 1996-2005 report (PDF, 1.74 MB). The results from the previous year's analysis are available in the 1995-2004 report (PDF, 0.74 MB).