- Millions of Americans are being urged to stay indoors on Friday as dangerous pollution spreads across large swaths of the country.
The National Weather Service issued the alert, warning that 16 US states will endure a dangerous mix of eye-burning ozone, wildfire smoke and fine particle pollution.
Air quality alerts have been issued in Arizona, California, Colorado, Connecticut, Indiana, Kentucky, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania and Rhode Island.
Authorities are advising people to limit strenuous outdoor activity, keep windows and doors closed and remain indoors if smoke or smog becomes thick in their area.
The alerts range from one-day advisories to warnings that remain in effect through Sunday night, depending on the location.
Ground-level ozone, commonly known as smog, is the primary concern across much of the East Coast, while wildfire smoke and fine particulate pollution are affecting parts of the West and northern New England.
Health officials warn that the polluted air can irritate the eyes and throat, trigger asthma attacks and make breathing difficult, particularly for children, older adults and those with heart or lung disease.
Residents in the affected states are being told to monitor local conditions and avoid prolonged time outdoors until the air begins to clear.
In the Northeast, the New York State Department of Environmental Conservation issued an Air Quality Health Advisory from 11am to 11pm ET Friday for New York City, Long Island and parts of the Hudson Valley, including New York, Bronx, Kings, Queens, Richmond, Nassau, Suffolk, Westchester and Rockland counties.
Officials said outdoor air quality is expected to exceed an Air Quality Index (AQI) value of 100 due to elevated levels of ground-level ozone, a pollutant created when emissions from vehicles, power plants and industrial sources react in sunlight.
A healthy AQI value is between zero and 50.
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