A surge in local ozone levels has promoted an extension of a health watch in the Valley.
The state Department of Environmental Quality reports ozone production levels Tuesday were rising at a rate that there may be residual issues on Wednesday.
Ozone is an invisible gas that is created when other pollutants in the air are heated.
Wednesday's high temperatures are forecast to be 93 to 98.
Ozone can aggravate existing respiratory conditions. A health watch is issued when ozone concentrations may approach unhealthy levels. People with health conditions, as well as the young and elderly, should limit time outdoors, especially in the late afternoon and early evening hours.