High ground-level ozone layers in New York City, Westchester and Rockland counties prompted the state's departments of Health and Environmental Conservation to issue air quality alerts Friday. The state issued a similar alert on Thursday that included Long Island as well.

When light hits some forms of pollution such as car exhaust, ground-level ozone forms. Though helpful high in the atmosphere, when breathed the ozone can cause respiratory problems, especially for children, the elderly and people with asthma.

For updates on ozone levels, call the Department of Environmental Conservation toll free at (800) 535-1345.