State extends ozone health watch for Phoenix area

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MESA, Ariz. (AP) -- The state has extended its air quality health watch for the Phoenix area due to elevated ozone levels. A health watch is issued when ozone concentrations may approach unhealthy levels.

The state Department of Environmental Quality tells the East Valley Tribune ozone production levels rose Tuesday at a rate that may lead to residual issues on Wednesday.

Ozone is an invisible gas that is created when other pollutants in the air are heated. Ozone can aggravate existing respiratory conditions. People are urged to limit outdoor activities during an air quality health watch.