An air quality alert was in effect Monday for several Chicago-area counties due to 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 will be in effect until midnight CDT Monday night,” the alert states.
MORE: Chicago Public Schools begin 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 levels of ozone and/or particulate matter are expected to be at or above the ‘unhealthy for sensitive groups’ category of the Air Quality Index for several days.”
On a Day of Action on Air Pollution, people with lung disease and other risk factors such as asthma, children and teens, older adults and people who are regularly active outdoors for six or more hours a day should reduce their outdoor exposure during the alert, officials said.
People who are concerned about being infected should watch for the following symptoms: wheezing, coughing, rapid heartbeat, fatigue, chest pain, and shortness of breath. If symptoms worsen, you should call your doctor or 911.
As of 7 a.m., Chicago’s air quality was “moderate,” with a PM2.5 reading of 55, according to AirNow.gov.
According to the NWS, the poor air quality alert is expected to be in effect “at least through Monday.”
What is PM2.5?
According to the EPA, “PM stands for particulate matter (also called particulate pollution): the term for a mixture of solid particles and liquid droplets present 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 that they can only be detected with an electron microscope,” the EPA says.
PM2.5 specifically refers to “fine inhalable particles, typically 2.5 micrometers or less in diameter.” For comparison, the average diameter of a human hair is about 70 micrometers, 30 times larger than these particles.
PM2.5 is one of the 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
On Monday at 12 p.m., 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. On Tuesday, excessive heat warnings will go into effect for the entire region.
On Monday, temperatures are expected to reach 35°C, with temperatures felt around 38-40°C, Jeanes said. Tuesday will be even hotter, with a high of 37°C and heat indices reaching up to 43°C.
According to NBC 5’s storm team, the record high temperature for Monday and Tuesday was 97 degrees, set in 1973.
“Be prepared to drink plenty of fluids, stay in air-conditioned rooms, avoid the sun, and check on your loved ones 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 deadly temperatures in minutes.”
“This is the warmest air we have experienced so far this summer,” the NWS said in a message posted on X, the platform formerly known as Twitter.
Tuesday’s forecast calls for early morning and evening thunderstorms, Jeanes said, with northern Illinois facing a “marginal” risk of severe weather, rated at level one out of five on the Storm Prediction Center’s scale. Scattered thunderstorms that develop could contain lightning, heavy rain and strong, damaging winds, the NWS said.
According to the Office of Emergency Management and Communications, 250 cooling centers across the city of Chicago are expected to be activated Monday and Tuesday.
