Ozone season has begun.

High levels of ozone pose health risks for everyone, and over half of the population is considered especially sensitive to ground-level ozone, says the Air Quality Partnership, administered by the Delaware Valley Regional Planning Council, which alerts the public when levels become dangerous.

We all cause it. The bright sunlight and high temperatures of summer react with pollution emitted by our motor vehicles, power plants and other things that burn fuel — even your lawn mower — to form high levels of ground-level ozone. Most of us call it smog.

Currently, the Delaware Valley does not meet the federal air quality standards for ground-level ozone.

With stronger standards instituted by the federal Environmental Protection Agency last year — albeit not strong enough, say some environmental and health advocates — the region will likely have more “Code Orange” days this year — 35 to 70, the partnership estimates.

On Code Orange days, those who are considered “sensitive” should limit strenuous outdoor activities. On Code Red days, that applies to everyone.

Daily air quality forecasts and tips for reducing air pollution are available at the partnership’s website or by calling 1-800-872-7261.

There's more information on the website of the Clean Air Council.