The Great Smoky Mountains National Park has recorded unhealthy levels of ozone pollution every day in August through Monday, Aug. 12.

Monday marked the 33rd time this year that unhealthy levels have been reached, posing a threat to the health of park visitors. Park managers emphasized that this advisory is specifically for higher elevation areas while ozone levels at lesser elevations outside the park may be lower.

The maximum 8-hour ozone averages measured at the park’s air quality stations yesterday Aug. 11 were 97 ppb at Cove Mountain (elevation 4,150 feet) and 99 at Look Rock (2,700 feet). At 9 a.m. Aug. 12, preliminary data recorded 86 ppb at Cove Mountain air quality monitoring station located at 4,150 feet.Unless there are major storm events or fronts passing through that would clean the air, exceedences are expected at other monitoring sites as the day progresses. Under federal and state standards in Tennessee and North Carolina, an 8-hour average ozone concentration of 85 ppb or greater is unhealthy. Natural ozone levels are estimated to be 20-40 ppb.

The U.S. Environmental Protection Agency (EPA) has identified several groups of people who are at risk from ozone exposure: those with respiratory problems such as emphysema, asthma, and chronic bronchitis; individuals engaging in heavy outdoor exercise either recreationally or at work as well as children at play; and a few otherwise healthy individuals who are especially sensitive to ozone and suffer greater loss of lung function than the general population. These visitors may wish to refrain from strenuous outdoor activities while this condition is in effect.

Ozone, considered a secondary air pollutant, is formed from primary emissions of nitrogen oxides (from coal-fired power plants, motor vehicles and factories) and volatile organic compounds in the presence of sunlight.

Ozone pollution is a powerful respiratory irritant in some people, causing shortness of breath, coughing, wheezing, scratchy eyes, nose, and throat, and chest pain while breathing deeply. Visitors experiencing these symptoms are advised to reduce strenuous outdoor activity and take shelter indoors.

Ozone pollution also is causing visible leaf injury to 30 species of vegetation at the Park such as black cherry, yellow-poplar, and tall milkweed. Typically, ozone levels in the higher elevations of the Smokies remain at dangerously high levels for a more extended period of each day than occurs in low elevations where the levels generally spike in late afternoon than drop rapidly in the evening.

The Park is now presenting air quality monitoring data to the public through a new computerized display located at Sugarlands Visitor Center and on its World Wide Web Site at www2.nature.nps.gov/ard/parks/grsm/grsmcam/grsmcam.htm. The data includes information on current visibility measurements, ozone pollution concentration levels, particulate matter, and real time digital camera pictures taken from the Look Rock Air Quality Monitoring Station.