An air quality alert was in effect Monday for multiple Chicago area counties amid dangerous heat and humidity levels.
The alert, from the National Weather Service, was initially issued Sunday and applies to Lake, McHenry, Kane, DuPage, Central Cook, Kendall, Grundy and Northern Will Counties.
"The Illinois Environmental Protection Agency has determined that an Air Pollution Action Day will be declared for the greater Chicago Metropolitan Area and is in effect until midnight CDT Monday night," the alert said.
MORE: Chicago Public Schools begins first day of 2024-25 school year in extreme heat
According to the NWS, an "Air Pollution Action Day is declared when weather conditions are such that widespread ozone and or particulate levels are expected to be at or above the Unhealthy for Sensitive Groups category of the Air Quality Index for multiple days."
During an Air Pollution Action Day, individuals with pulmonary illnesses and other risk factors such as asthma, children and teens, older adults, and individuals who are routinely active outdoors for six or more hours per day should reduce exposure outdoors during the alert, according to officials.
Those who worry about being affected should look out for the following symptoms: wheezing, coughing, a fast heartbeat, fatigue, chest pain and shortness of breath. If symptoms worsen, you should call your doctor or 911.
Local
As of 7 a.m., Chicago's air quality stood at "moderate," with a PM2.5 of 55, according to AirNow.gov.
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According to the NWS, the alert warning of poor air quality was expected to be in place "through at least Monday."
What is PM2.5?
According to the EPA, "PM stands for particulate matter (also called particle pollution): the term for a mixture of solid particles and liquid droplets found in the air."
"Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope," the EPA states.
PM2.5 in particular involves "fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller." By comparison, the average human hair strand is about 70 micrometers in diameter, or 30 times larger than these particles.
PM2.5 is one of five major air pollutants regulated by the Clean Air Act, which also includes ground-level ozone, carbon monoxide, sulfur dioxide and nitrogen dioxide.
Extreme heat Monday, Tuesday
At 12 p.m. Monday, a heat advisory will go into effect for the entire Chicago area, with Cook County under an excessive heat warning, the National Weather Service said. Tuesday, excessive heat watches will go into effect for the entire area.
Monday was expected to hit a high of 96-degrees, with "feels-like' temperatures closer to 100-105 degrees, Jeanes said. Tuesday would be even hotter, with a 98-degree high and heat indices up to 110-degrees.
According to the NBC 5 Storm Team, the record high for Monday and Tuesday was 97 degrees, set in 1973.
"Be prepared to drink lots of fluids, stay in air-conditioned rooms, stay out of the sun and check up on relatives and neighbors," the NWS warned. "Young children and pets should never be left unattended in vehicles under any circumstances. This is especially true during warm or hot weather when car interiors can reach lethal temperatures in a matter of minutes."
"This is the hottest air that we've experienced so far this summer," the NWS said in a message posted to X, the platform formerly known as Twitter.
Tuesday's forecast comes with a chance for early morning and evening thunderstorms, Jeanes said, with northern Illinois at a "marginal" risk of severe weather, which ranks as level one of five on the storm prediction center's scale. Any scattered storms that do develop could contain lightning strikes, heavy downpours and gusty, damaging winds, the NWS said.
250 Cooling centers across the city of Chicago were expected to be activated Monday and Tuesday, according to the Office of Emergency Management and Communications.
