May 13, 2010 6:01 AM
MESA, Ariz. (AP) State environmental officials have issued an ozone air quality health watch for Thursday in metro Phoenix.
Ozone production and accumulation are expected to increase as temperatures rise and cloud cover is expected to be minimal.
A health watch is issued when ozone levels may approach the federal standard.
Ozone is a colorless gas that can irritate the eyes, nose and lungs and worsen existing heart and respiratory ailments.
Information from: East Valley Tribune, http://www.eastvalleytribune.com