Breathing problems? Unhealthy ozone levels could by why

By Kathy Helms-Hughes
STAR STAFF
khughes@starhq.com

   If you've had difficulty breathing while outside conducting strenuous activities, or if your asthmatic child has been complaining of shortness of breath, don't take it lightly. There's a reason for it.
   Ozone levels reached unhealthy concentrations this week in the Tri-Cities and ranged from moderate to unhealthy in the Great Smoky Mountains National Park, according to data provided by Tennessee Department of Environment and Conservation to the U.S. Environmental Protection Agency.
   Ozone, the main ingredient of smog, can cause a number of respiratory problems, and active children who spend a great deal of time outdoors in hot weather are at highest risk from exposure.
   Persons with asthma or chronic respiratory diseases such as emphysema or bronchitis generally experience health effects at lower ozone levels than less sensitive persons, according to EPA, and when ozone levels are high, asthmatics are more susceptible to attacks requiring medical attention.
   Small children, whose lungs are still developing, may suffer reduced lung function when they grow to adulthood if exposed to repeatedly high though short-term ozone concentrations. Active adults also are more at risk than less-active ones.
   Ozone increases one's sensitivity to allergens such as pollen and can cause coughing, a feeling of irritation in the throat, or uncomfortable sensation in the chest, according to EPA. It also can reduce lung function, making it more difficult to breathe as deeply or as vigorously as one normally would.
   Ozone levels usually are lower in the morning or evening, and limiting strenuous activities to those times can reduce the chances of being affected.
   Twice in the year 2000, monitoring stations in Kingsport detected ozone levels over the concentration standard of 120 parts per billion over a one-hour period. Three days over the limit in three years would put the Tri-Cities in "non-attainment" status under the Clean Air Act. The ozone season extends from May through September.
   Tod Hyslop of the National Weather Service in Morristown said Wednesday that there is a "tremendously impressive upper-level ridge," or high pressure area, which contributes to increases in particulates due to lack of motion in the atmosphere.
   "There's very little wind involved in them," he said, so there's not a lot of dispersion of pollutants. The wind flow is like a river carrying the particulates downstream, according to Hyslop. "When the wind stops blowing very much, these particulates just kind of hang around in the air."
   Hyslop said his meteorological chart indicated that while the air is "actually kind of moving along a little bit, it's not tremendous."
   Also, cloud cover such as that observed Wednesday morning slows the penetration of solar radiation which comes in and mixes up particulates that have settled near the ground overnight, he said.
   "We don't get quite the heating that we need to get the convection where the air moves from the ground, rises through the day, and then you get nice clean air that is pulled down."
   Rainfall helps disperse pollutants, but, Hyslop said, "I can't promise anything that's really going to help us in a big way" over the next several days, though there may be enough to settle the dust.
   "As rain falls its pulling cleaner air from aloft and you do get a dispersion. It's like if you have a stinky, nasty swimming pool and you bring nice fresh water in -- you decrease the number of pollutants in there," Hyslop said.
   Grady Wray of TDEC's Division of Air Pollution Control in Johnson City said that while the Tri-Cities has not exceeded ozone levels yet, "we have skirted them. We've gotten a couple of high readings. If we get some exceedences, we've got some problems. But right now we don't."
   Ozone is formed when nitrogen oxides from automobiles and coal-fired plants combine with volatile organic compounds, Wray said. "In the presence of sunlight, it turns into ozone."
   When the weather is cooler, ozone is not as big a problem as it is in the summer when it starts to heat up, he said.
   "Ozone is not something that's generated here and stays here. We impact other states and they impact us," he said. "We do have some problems with it occasionally."