Reprinted from the Health District's quarterly publication mailed to district residents - Summer 2005

Ozone is like cholesterol – there’s a good kind and a bad kind. And the trick is knowing the difference so you can do something about it.

In the Earth’s upper atmosphere, ozone is our friend. It protects us from the sun’s ultraviolet rays. But its cousin, ground-level ozone, is no protector. When inhaled, this type can make you cough or struggle to breathe, depending on your sensitivity.

Ground-level ozone affects those with asthma, but it can also take its toll on active, healthy adults and children. People who exercise breathe faster and take in as much as five times more air, allowing more ozone to enter deep into the lungs where it can damage tissue.

Ozone also can exacerbate symptoms in people with allergies. “With a moderate level of ozone, they will have more trouble breathing, more itching of the eyes and nasal symptoms,” says Dr. Janet K. Seeley, an asthma and allergy specialist in Fort Collins.

Ground-level ozone is formed when pollutants, such as fumes from cars and smokestacks, react chemically with sunlight. Summer is prime time for ozone along the Front Range because conditions needed to form it – fumes and heat – are ripe. As Fort Collins’ senior environmental planner Lucinda Smith puts it, “things bake.”

Mention ozone and people often assume it’s a big-city problem. True, Denver has on occasion violated the federal ozone standard, but as its neighbor 60 miles to the north, Fort Collins shares the problem, too. That’s partly because of air flow along rivers, says Brian Woodruff, environmental planner with the city of Fort Collins. At night, cool air – and pollution – travels downstream from Fort Collins to Greeley and from Denver to Greeley. The flow reverses during the day, bringing the air mixture with it.

To find out air quality information for Fort Collins, residents can check the Coloradoan’s weather page or tune in to the city’s Cable Channel 27 for high ozone alerts.

On days with high ozone levels, it’s best to limit outdoor activity to early morning or after traffic rush time, Dr. Seeley says. “If you experience shortness of breath, stop exercising. And then see if your symptoms correlate with a high air pollution day,” she says. “If you’re especially short of breath and don’t know why, go to an urgent care or ER for help.”

From an environmental standpoint, educating consumers about the causes of ozone is the first step to curbing it, experts say. Two known contributors are a leaky gas cap on your car, which through vapors can let out about a gallon of gasoline over two weeks, and a gas-powered lawn mower, which in an hour of use, scientists say, can pollute as much as 40 late-model cars.

For its part, the city is urging people to mow when the sun is low (early or late in the day) and to stop at the click when refueling. These and other small changes, they hope, will let residents breathe a little easier.

“A lawn mower engine seems like a trivial thing, but one hour of lawn mowing has a big impact on air quality,” says Woodruff.