Evaluating Ozone in the Eastern US
The NPS also reported a short-term downward trend in ozone in its 2004 Annual Data Summary Report for Great Smoky Mountains and other eastern parks. Ozone is an air pollutant that causes human health problems by aggravating respiratory diseases such as asthma. It also causes damage to vegetation by injuring plants and trees in national parks and reducing agricultural crop yields.
Lower NOx emissions are also expected to reduce nitrogen deposition, which can cause the unnatural fertilization of ecosystems and acidification of surface waters and soils that affects aquatic plants and animals. The NPS has recently documented decreasing levels of nitrogen in deposition at three parks in the East; Great Smoky Mountains, Shenandoah, and Indiana Dunes.
The EPA expects NOx emissions to decrease another 50% from the 2003 level by 2015. Eastern parks will continue to benefit from these NOx control programs.