An Orange Air Quality Alert means there are unhealthy pollution levels for sensitive groups.
The Pennsylvania Department of Environmental Protection declared a Code Orange Air Quality Alert for ozone for Philadelphia, Bucks, Montgomery, Chester, and Delaware counties.
This comes as the Philadelphia region expects to hit record-breaking highs during a heat wave this week.
The New Jersey Department of Environmental Protection also issued a Code Orange for Southwestern New Jersey, including Burlington, Cumberland, Middlesex, Mercer, Monmouth, Ocean and Salem counties.
An Air Quality Action Day alert is also in effect for Bergen, Passaic, Hudson, Essex and Union counties in New Jersey until 11 p.m. Tuesday.
In Delaware, a Code Orange Air Quality Action Day has also been issued. Officials say a temperature inversion is confining pollutants near the surface early in the day. They also said light to moderate southwesterly to westerly winds will transport regional pollutants into the First State, adding that mostly sunny skies and highs in the mid-90s will enhance ozone development.
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Parts of New York, Maryland and Connecticut are also under alerts for air quality.
An Air Quality Action Day is declared when the AQI is forecasted to be Code Orange or higher.
The effects of air pollution can be minimized by avoiding strenuous activity or exercise outdoors, according to NOAA.
On an Air Quality Action Day, young children, the elderly, and those with respiratory problems, such as asthma, emphysema, and bronchitis, are especially vulnerable to the effects of air pollution and should limit outdoor activities.
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