When we talk about ozone as an air quality problem, we're talking about ground-level ozone. Although ground-level ozone has the same chemical makeup as stratospheric ozone (the protective ozone layer), ozone in our lower atmosphere has a much different effect. Ground-level ozone is the main component of smog, and is a respiratory irritant, which means that it's hazardous to human health. It can also harm vegetation.

Ozone is a secondary pollutant that forms when other pollutants in the atmosphere (called precursors) combine in certain weather conditions. Nitrogen Oxides (NOx) and Volatile Organic Compounds (VOCs) "cook" in the hot Texas sun to create ozone (O3).

What CAUSES Ozone?

NOx and VOCs are mostly caused by human activities. Burning fossil fuels releases NOx, and many household and industrial chemicals release VOCs. Some VOCs are biogenic, or emitted from plant life. While Austin has significant amounts of biogenic VOCs, these are not the cause of our ground-level ozone problem.

In Central Texas, emissions from cars and trucks are the largest contributor to ground-level ozone. Other sources of pollution include factories, construction equipment, dry cleaners, print shops, and household activities like mowing your lawn. That means each and every one of us can DO SOMETHING to help prevent ozone pollution.

Ozone and your HEALTH

Ozone irritates the lining of the lungs, making it difficult for some people to breathe. Those most affected by ozone are asthmatics, seniors and people with compromised respiratory systems. Children are especially vulnerable, since they breathe at a faster rate than adults and can take in a larger volume of polluted air. The effects of high ozone concentrations (shortness of breath, coughing, and burning sensations in the eyes and lungs) can also be felt by healthy adults, particularly when they exercise outside.

So does a high-ozone day mean you can't be outside? Not necessarily, since ozone affects different people in different ways and amounts, and many common allergens are also elevated on high-ozone days. If you believe your symptoms may correlate with high ozone levels, talk with your doctor.

If you are one of the many people affected by ozone, try staying indoors on ozone action days, or limiting your outdoor activity. If you enjoy exercising outdoors, try to do so in the morning when ozone concentrations are usually lowest. Encourage susceptible children to play indoors or find less strenuous outdoor activities (light gardening, flying kites, frisbee, etc).

So what's our ozone situation here in Austin?