WHITE PLAINS — Health officials are warning people to take it easy in the heat today across metropolitan new York and the Lower Hudson Valley because of an elevated level of pollutants in the air.

Those at risk of developing breathing problems include the very young, those with respiratory ailments such as asthma and heart disease, and those who strain themselves outdoors.

The air-quality alert is in effect until 10 p.m.

State officials explained that summer heat can lead to the formation of ground-level ozone — a major component of smog that is not to be confused with the protective layer in the upper atmosphere that screens ultraviolet radiation.

Ground-level ozone builds in the summer heat with automobile exhaust and industrial emissions.

Symptoms of exposure include short breath, chest pain and coughing.

People who have trouble breathing should call a doctor.

Call the state’s Air Quality Hotline at 1-800-535-1345 for more details.