Ground-level Ozone happens when:

Ground-level Ozone (O₃) is created when nitrogen oxide gases (NOx) react with volatile organic compounds (VOCs) on hot, sunny days. The sources of these compounds are found in things we use everyday:

• Cars and trucks
• Power plants and factories
• Gasoline vapors
• Paints
• Cleaners and other solvents
• Gasoline-powered lawn equipment

These gaseous compounds mix like a thin soup in the atmosphere, and when they interact with sunlight, ozone is formed. They are also present at low levels in many indoor environments.

An Ozone Action Day is a day when the Ozone levels are too high and therefore unhealthy. This is a day when people should avoid being outside. High ozone concentrations usually occur in the early afternoon and continue into early evening from May through September. Ozone alerts are announced by the New York State Department of Transportation when ground-level ozone concentrations are forecast to be unhealthful. Click here to sign up for Ozone Alerts.

On Ozone Action Days, we all need to be especially aware of our own contribution to the problem and work to reduce it. Click here to learn what you can do to help prevent Ground-level Ozone.

Click on the link below to see ozone pollution concentration maps.

Animated and static ground-level ozone pollution
concentration maps:

• Ozone Concentration Map - Today