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Ozone: Good up High, Bad Nearby

What is ozone?
Ozone (the molecular formula is O3) is a gas that occurs naturally both in the earths upper atmosphere and at ground level. Ozone can be good or bad, depending on where it is found.

Good ozone
Ozone occurs naturally in the earths upper atmosphere 10 to 30 miles above the earths surface where it shields us from the suns harmful ultraviolet rays.

Bad ozone
Higher levels of ozone are created by the combination of pollutants from many sources. Utility companies, industry, cars, gasoline-powered lawn equipment, paints, solvents, and even plants and trees all contribute to the formation of ozone. In the summer, higher levels of ozone form in the presence of heat and sunlight. Weather is a key factor in the formation of ozone.

When is ozone season?
Typically ozone forms on a cloudless day when temperatures are high and winds are stagnant. In our region, high ozone levels can be expected between the months of May and September.

What is our region's history?
In 2004, EPA designated Sullivan and Hawkins Counties as being in non-attainment of the national ambient quality standard for ground-level ozone.This is with regard to a new, more stringent standard known as the 8-hr standard, set at 80 ppb.  Prior to that, the area had been in attaiment for many years with the previous standard (attainment defined as no more than 4 exceedances in a 3 year period of time).  However, two exceedances in June of 2000 raised our awareness of the issues associated with nonattainment and led to the formation of the Ozone Action Partnership.  Currently, our non-attainment requirements have been deferred under an Early Action Compact with the EPA (see links elsewhere on this website).  To avoid nonattainment altogether, the ozone levels measured at the two state-run monitoring sites in the region must meet the attainment criteria by the end of 2007.

How does ground level ozone affect us?
Even at low levels ozone can cause a number of respiratory effects. Active children are at highest risk because they spend a lot of time outdoors in the summer. They breathe faster and have less body mass. Active adults who play hard and work hard outside are also at risk, as well as the elderly and those people with asthma or other respiratory diseases.

Ozone exceedances can also impact the economic health of our region. Should we have another day where ozone levels are high, our region could be designated as non-attainment. This could jeopardize our ability to attract new business or grow the ones we have, we could lose federal highway dollars, and the State could impose certain actions such as a car inspection program. Although many metropolitan areas in the U.S. will be designated as non-attainment, this is not a label we want on our region.

What can we do?
Our region formed an Ozone Action Partnership in 2001. Government, industry, academia, and the medical community have organized this volunteer effort in order to (1) notify the public of any expected high ozone levels and (2) work to limit peak ozone levels on high-ozone days. Working together and by voluntarily doing certain things, we can make a difference in our air quality. The Tennessee Department of Environment and Conservation meterologists issue a daily forecast of expected ozone levels for the following day.  When high ozone levels are forecast, the Partnership will annouce an Ozone Action Day thru our local media and email distribution list.  The public and local businesses will be asked to:

• Delay mowing your yard or using gasoline-powered lawn equipment until after 6 p.m.
• Avoid burning yard clippings, leaves or brush.
• Drive your newest and most fuel-efficient car.
• Carpool to work, school, or lunch.
• Eliminate a trip you can put off to another day.
• Fill up your car in the evening, rather than during the day. 
• Telecommute.
• Avoid areas where your vehicle will idle a long time like drive-thrus or congested intersections.
• Conserve energy.
• Put industry action plans into place to reduce nitrogen oxide emissions.

Why should we implement an ozone action program? We can't control the weather, but by working together voluntarily, we can keep our air clean and have a prosperous economy.