High ozone levels have prompted Great Smoky Mountains National Park officials to issue an air pollution advisory for today and Saturday. So if you're visiting the park, you might want to ease back on your physical activity, especially if you already have respiratory problems.
Under federal and state human health standards in Tennessee and North Carolina, an 8-hour average ozone concentration of 76 parts per billion or greater is considered unhealthy to certain people. At 9:00 a.m. this morning the 8-hour average ozone levels in the park ranged from 87 ppb at Clingmans Dome to 77 ppb at Look Rock.
The U.S. Environmental Protection Agency has identified several groups of people who are at risk:
* those with respiratory problems such as emphysema, asthma, chronic bronchitis and heart problems;
* individuals engaging in strenuous outdoor exercise either recreationally or at work;
* children at play;
* the elderly, and;
* a few otherwise healthy individuals who are especially sensitive to air pollution and suffer greater loss of lung function than the general population.
Park officials say that this is the 11th unhealthy day that the park has documented in 2008, but this is the first advisory issued. The previous exceedances began so late in the day that visitor exposure would be minimal.
Natural ozone levels are estimated to be between 15-40 ppb. Natural fine particle levels are estimated to be 3-5 μg/m3. Ozone pollution also is causing visible leaf damage to at least 30 species of vegetation at the Park. Particle pollution contributes to acid deposition, which is harming streams and forests, and regional haze which impairs viewing scenery.
Real-time Park Air Quality information is available at this site.