Ground-level ozone is the pollutant in question.

By Michael Woyton (Patch Staff) - Updated August 3, 2017 10:58 am ET

HUDSON VALLEY, NY — Greater than normal air pollution expected for Thursday has led the state Department of Environmental Conservation to issue an air quality health advisory for most of the Hudson Valley. The air quality alert is in effect until 11 p.m. Thursday for Dutchess, Orange, Putnam, Rockland, Ulster and Westchester counties.

Air quality levels in outdoor air are predicted to be greater than an Air Quality Index value of 100 for the pollutant of Ground Level Ozone. The Air Quality Index — or AQI — was created as an easy way to correlate levels of different pollutants to one scale. The higher the AQI value, the greater the health concern.

When pollution levels are elevated, the New York State Department of Health recommends that individuals consider limiting strenuous outdoor physical activity to reduce the risk of adverse health effects. People who may be especially sensitive to the effects of elevated levels of pollutants include the very young and those with preexisting respiratory problems such as asthma or heart disease. Those with symptoms should consider consulting their personal physician.

A toll-free air quality hotline has been established so New York residents can stay informed on the air quality situation. The toll free number is 1-800-535-1345.