![]() Ozone, the main ingredient of smog, presents a serious air quality problem in several National Park Service areas. Even at low levels, ozone can cause health effects.
Ozone is mainly formed by chemical reactions between volatile organic compounds (VOCs) and oxides of nitrogen in the presence of sunlight and higher temperatures. The human-caused sources of VOCs and nitrogen oxides are industrial and automobile emissions. Ozone concentrations can be transported hundreds of miles and affect remote areas of the country. Ozone can irritate your respiratory system. When this happens, you may cough, feel irritation or soreness in your throat, or experience chest tightness or pain when taking a deep breath. Reduced lung function can make it more difficult for you to breathe as deeply and easily as you normally would. This is especially true when exercising at higher elevations. Exposure to ozone can also increase the susceptibility of the lungs to infections, allergens, and other air pollutants. Medical studies have shown that health problems caused by ozone may continue long after exposure has ended. When ozone levels are very high, everyone should be concerned about ozone exposure. In general, as concentrations of ground-level ozone increase, both the number of people affected and the seriousness of the health effects increase. Several groups of people are particularly sensitive to ozone, especially when they are active outdoors. Ozone levels are higher outdoors, and physical activity causes faster and deeper breathing, drawing more ozone into the body. People particularly sensitive to ozone include:
What are National Park Service ozone health advisories?The NPS issues ozone health advisories when ozone concentrations exceed, or are forecasted to exceed, the National Ambient Air Quality Standard. The ozone health standard is an 8-hour average concentration of 70 parts per billion (ppb). NPS ozone health advisories are based on the EPA air quality index levels shown below. View ozone health advisories issued for National Park Service areas.
![]() Understanding Ozone Health Advisory Levels
Some plants are actually sensitive to ozone at levels well under the national health standards. Lichens, mosses, and liverworts often are most sensitive within an ecosystem and can serve as early indicators of air pollution effects. Plants can also be injured by ozone, which damages their leaves or needles and weakens plants’ ability to fight off disease and insect infestations. Learn more » |
Last updated: July 24, 2024