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Drive into a major city on a hot summer day and you’re likely to see a white or brown haze instead of a clear, blue sky. It’s not uncommon and it’s caused by air pollution, sometimes from hundreds of miles away. Now imagine breathing the harmful particles that make up that smog deep into your lungs.

Air pollution really refers to any harmful gas or particulate found in the air we breathe. Two pollutants in particular are of concern to the Middle Tennessee area – ozone and particulate matter. These two threats are caused by some of the same things: vehicle emissions, power plant smoke, spilled solvents, and small engines (such as lawn equipment), and they can pose a serious risk to your health.

Particulate Matter

Particulate matter is a mixture of extremely small particles and liquid droplets in the air. These particles are so small that they’re just a fraction of the size of a human hair, but they pose serious health threats because they can pass through the nose and throat, and travel deep into the lungs and bloodstream.

These particles are produced whenever fuels such as coal, oil, diesel or wood are burned. So every time someone burns a woodstove, drives a car, or uses a lawnmower, dangerous particles are being released into the air we breathe.

Ozone

NOx + VOCs + Sunlight = Ozone

Ozone is a gas created from nitrogen oxides and Volatile Organic Compounds (VOCs) chemically reacting with the sun. The reason you see more smog and ozone alerts in the summer is that the strong light from the sun “cooks” the chemicals found in fuels, oil-based paints, aerosol sprays, and the evaporation of gasoline.

Cars and trucks commuting to and from major metropolitan areas are a major contributor to the ozone problem. The emissions from thousands of cars - paired with warm weather - lead to ozone alert days and diminished air quality, and put everyone’s health at risk.

These emissions can be transported by winds and can form ozone pollution hundreds of miles away from the original sources. Transported emissions can cause high ozone levels even in rural areas; places such as the Great Smoky Mountains and the Shenandoah national parks have higher ozone levels than some cities due to transported emissions.

Good Up High, Bad Nearby

Ozone occurs in two layers of the Earth’s atmosphere: One level protects us, while the other can cause serious damage.

Ten to 30 miles above the surface of the Earth, the stratospheric ozone layer protects us from the sun’s harmful ultraviolet rays. Closer to home in the troposphere, which is from the ground up to 10 miles above the Earth’s surface, ozone can damage human health, crops and buildings.

What Pollution Means for Your Health

Air pollution is a serious issue here in Middle Tennessee. Ground-level ozone and particle pollution can reduce lung function, cause wheezing, coughing, shortness of breath and asthma, and trigger asthma attacks. Everyone is at risk of experiencing the adverse effects of ground-level ozone, but people with heart or lung disease, children, the elderly and those who are active outdoors are at a greater risk.