Air Quality Information

What Is Ozone?

There are actually two different kinds of ozone: good ozone and bad ozone. Ozone is a gas that occurs in both the Earth's upper atmosphere and at ground level. In the atmosphere it is good. On the ground, it is not.

Good Ozone

This is the ozone that occurs naturally in the Earth's upper atmosphere, 10 to 20 miles above the Earth's surface - where it shields us from the sun's harmful rays. You've heard about the hole in the ozone layer? This high layer is what scientists are concerned about.

Bad Ozone (Smog)

Down here where we are, in the Earth's lower atmosphere, ozone is formed when pollutants from cars, chemical plants, power plants, and other sources react chemically in the presence of sunlight. Ozone levels go up in summer when the weather needed to form ground-level ozone (lots of sun and hot temperatures like we have in Northwest Louisiana) occurs.

Where Does Bad Ozone Come From?

Ozone isn't emitted directly into the air from smokestacks and tailpipes, but the chemicals that create ozone - Nitrogen Oxide (NOx) and volatile organic compounds (VOCs) - are. Major sources of NOx are vehicles, utilities, and industry. Man-made sources of VOCs include industrial and commercial processes, vehicles, and solvents.

The process that causes ozone looks like this:

VOC + NOx + sunlight = Ozone

In high enough quantities, Ozone can:

• Aggravate asthma
• Cause reduction in crop yields
• Create a white or brown haze
• Damage the foliage of trees and other plants
• Irritate your respiratory system

Ozone in the Caddo / Bossier / DeSoto Parish area is not high enough to cause those problems, and we want to keep it that way, but we need your help in doing it.