An air quality alert has been issued for the Lower Hudson Valley, including Westchester, Rockland and Putnam, for today. A warning was also issued yesterday. The state departments of Health and Environmental Conservation issued the warning because of unhealthy levels of ozone in the air. Ozone is the main component of smog and it comes mainly from automobile exhaust. Exposure can cause short-term health effects such as irritation to the eyes, nose and throat, coughing, sneezing, runny nose, and shortness of breath. For more information on air quality, call the state hotline at 800-535-1345 or visit the DEC website at http://www.dec.ny.gov.