Heat and air quality heath advisories in effect until 11 p.m.

It’s a good day to stay indoors.

A heat advisory and an air quality alert are in effect for our region today.

With forecast temperatures in the 90s today and high humidity levels, today’s heat index is forecast to reach about 100, according to the National Weather Service, which said the heat advisory will be in effect from 11 a.m. until 8 p.m. tonight.

The New York State Department of Environmental Conservation has issued an air quality health advisory for Suffolk, Nassau, NYC, Westchester and Rockland counties. The air quality advisory is in effect from 11 a.m. through 11 p.m. tonight.

But before you crank up your air conditioning, consider this: the heat wave is expected to put a stress on the island’s electric system, according to the L.I. Power Authority.

LIPA is anticipating a high demand for electricity and said though it “has more than sufficient capacity” to meet customers’ needs the extra demand place on electrical equipment in a heat wave may cause localized outages.

LIPA said in a statement it has “extra crews available to restore power in a quick and safe manner.”

The power authority asks customers to avoid unnecessary use of electrical appliances during peak hours.

Riverhead and Southold towns, as well as Suffolk County have opened cooling centers for residents who need a break from the heat. See related story for cooling center information. 

Today’s outdoor air quality levels are predicted to be greater than an air quality index value of 100 for the pollutant of ground-level ozone. The forecast air quality index for ground-level ozone today on Long Island is 101, which is unhealthy for sensitive groups, including very young children, the elderly and people with pre-existing respiratory problems such as asthma or heart disease.

The New York State health department recommends that people in the posted areas consider limiting strenuous outdoor physical activity to reduce the risk of adverse health effects.

The federal environmental protection agency warns that elevated ground-level ozone can cause:

irritation of the airway, coughing and pain when taking a deep breath;

wheezing and breathing difficulties during exercise or outdoor activities;inflammation, which is much like a sunburn on the skin;

aggravation of asthma and increased susceptibility to respiratory illnesses like pneumonia and bronchitis; and

permanent lung damage with repeated exposures.

Ground level ozone is produced by by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight, according to EPA.gov. Emissions from industrial facilities and electric utilities, motor vehicle exhaust, gasoline vapors, and chemical solvents are some of the major sources of NOx and VOC.

Health officials advise limiting outdoor activities during the period of the alert.

The state has established a toll-free air quality hotline: 1-800-535-1345.