An ozone air quality health watch has been issued in the Valley for Wednesday. The Arizona Department of Environmental Services issues a health watch when ozone levels may approach federal standards.
Ozone is an invisible gas that is created with pollutants in the air are heated.
The Valley is under an excessive heat warning, with temperatures Wednesday expected to be well above 110. Ozone can aggravate existing respiratory issues such as asthma.
The elderly, young and people with health conditions should limit time outdoors, especially in the afternoon when ozone creation is at a peak.