Extreme heat, unhealthy air hits Chicago Friday

Chicagoans face a dual threat of deadly heat and unhealthy air Friday, expected to be the hottest day so far this year.

Forecasters predict a heat index — a measure of temperature and humidity — that may reach 110 degrees.

The heat alone could be very dangerous, and residents, especially seniors and those with health conditions, are urged to seek shelter in air-conditioned spaces and stay hydrated. Chicago established community cooling centers, though they have limited hours.

The heat can exacerbate respiratory issues and cause a host of other health risks, including heat stroke.

“Heat still kills more people in the U.S. than any other weather hazard,” said Trent Ford, Illinois state climatologist.

State and national environmental officials also warn of high levels of ozone pollution through Friday, which can be particularly harmful to “sensitive” populations such as those with asthma and other conditions that affect breathing.

“Air pollution on top of that [heat] will add to that misery on top of the health risk,” said Brian Urbaszewski, environmental health director for the Respiratory Health Association.

The ozone smog levels, which often rise on sunny days, replace the high amounts of particulate pollution that recently blew into Chicago from the Canadian forest fires.

The Chicago area has seen a rash of extreme weather attributed to climate change in recent weeks.

Heat, however, has been a long-trending climate-related phenomenon that is not only making summer days hotter but also warming up average temperatures in the evenings, Ford said.

Decades ago, Chicagoans could enjoy some July evenings with temperatures dipping below 60 degrees and providing relief after hot days, according to data provided by Ford.

That’s no longer the case.

“With heat, it’s clear. Every single place on Earth is getting warmer,” Ford said.

One cooling center in Chicago, Garfield Center at 10 S. Kedzie Ave., is open 24 hours.

The others centers are open from 9 a.m. to 5 p.m., including: Englewood, 1140 W. 79th St.; King, 4314 S. Cottage Grove Ave.; North Area, 845 W. Wilson Ave.; South Chicago, 8650 S. Commercial Ave.; and Trina Davila, 4300 W. North Ave.

Chicago’s public libraries and Chicago Park District field houses are open during regular daytime hours.

Some health care clinics, including Oak Street Health, encourage residents to visit them to avoid the heat. Oak Street operates a dozen clinics across the city and more in the suburbs.

“We welcome our patients and community members who need to cool off,” Oak Street’s chief medical officer Ali Khan said.

Anthony Vazquez / Sun-Times

For suburban cooling centers and heat information, check county or local health and emergency management websites.

Some parts of Chicago and other cities will be much hotter, depending on factors including a scarcity of trees.

People living in so-called “heat island” areas will suffer the greatest heat stress. The urban areas are often characterized by a lack of trees and other greenery and often have more pavement that absorbs heat.

On Friday, hundreds of volunteers will be driving around the city with devices attached to their cars to take heat and humidity measurements as part of a national climate study on heat islands.

One bit of good news: The heat and humidity is expected to moderate over the weekend.

Brett Chase’s reporting on the environment and public health is made possible by a grant from The Chicago Community Trust.