Ozone Facts SWCAA News

Wednesday, October 15, 2014 - What is Ozone Anyway? Ozone (03) is made naturally in the atmosphere when three oxygen atoms join together to form a colorless gas. Ozone can have good or bad effects, depending on where it's located in the atmosphere. One way to remember this is, good up high, bad nearby.

The Good Ozone Layer: Earth's Sunscreen

The earth is wrapped in layers of air called the atmosphere. Good ozone is in the earth's upper atmosphere, 10 to 30 miles above the surface. Life couldn't exist without this protective ozone, which is also called the ozone layer.

The sun gives off light, heat, and other types of radiation. Too much UV (ultraviolet) radiation can cause skin cancer, cataracts, and harm plants and animals. Ozone high in the atmosphere absorbs, or takes in, some of the sun's harmful UV rays before they reach the ground. Just as sunscreen helps protect your skin from getting burned, ozone up high works like Earth's sunscreen.

What Causes Bad Ozone?

Bad ozone is found at ground level. In cities, it's made when emissions from vehicles, power plants, chemical plants, and other sources react with heat and sunlight. The hotter the day and the stronger the sun, the more ozone is formed. That's why ozone is usually worst on calm, hot summer afternoons. High levels of ozone are mainly a concern for people from April 1–September 30.

You're most likely to find high levels of bad ozone in urban areas. You might hear it called smog. However, other areas can also have high ozone levels when winds blow pollution hundreds of miles from their original sources.

Learn more about ozone by visiting AirNow