After a flood, mold sticks around and can make people sick

Dorothy Rosenthal couldn’t believe her eyes.

Four feet of water overwhelmed her basement in West Garfield Park, destroying everything in a storage area, laundry room and an office in July 2023.

A load of memories — from Mother’s Day cards from her two kids, to old toys, and other sentimental items were ruined. Her computer was destroyed. So was her washer and dryer and her boiler system.

That was just the beginning.

The storm “left mold, big black patches of mold,” she says. “Big bubbles, black bubbles on the wall.”

Almost three years later, Rosenthal finally has had the mold removed from her home, persistent black gunk that lined every wall of her basement.

It wasn’t just unsightly, the mold aggravated her asthma, a condition she’s been struggling with for about 20 years.

“It got to the point that … I saved all the washing for Saturday. And once I would wash, two days afterwards I wouldn’t be able to taste or smell,” Rosenthal says.

“I can now look forward to washing without being sick for two days after and I am grateful for that,” she says.

Rosenthal had to live with mold because she couldn’t afford to pay a private contractor thousands of dollars to get rid of it.

She’s not alone. Dozens of flood survivors turned to a West Side nonprofit that is using around $3.6 million in taxpayer money to help pay for flood-related damages and removal of harmful mold. Under the program, about 120 homes are expected to be repaired and remediated by the end of the year, according to the city.

The nonprofit, West Side Health Authority, was placed in charge of the program late last year by the city after federal money was awarded to Chicago in 2024.

Climate change brings more rain, more flooding, more mold

Rosenthal and her neighbors in Chicago and across Illinois are confronting the effects of more intense flooding and more severe weather. Climate change is contributing to thunderstorms that hit harder and more frequently, like ones that caused flooding in 70,000 West Side and suburban basements in summer 2023.

Those storms are also leaving behind serious health threats, including mold, which can make people sick. Tiny mold particles can enter the respiratory system, causing fatigue, rashes and other complications. People with compromised immune systems, respiratory illness and the very old or young can be affected more seriously.

“People will have totally different reactions,” says Dr. Sheetal Rao, an internal medicine doctor at UI Health. “It all has to do with your exposure and vulnerability.”

In one particularly serious condition known as hypersensitivity pneumonitis, patients have an allergic reaction to mold that can lead to scarring of the lungs, making it difficult to breathe, says Rush University System for Health pulmonologist Dr. Samuel Fox.

The problem with tackling mold as a public health threat is that there are many types of mold, too.

“The science is very complicated,” adds Dr. Arturo Casadevall, a professor of medicine at the Johns Hopkins School of Medicine. “There are a zillion black mold species. So, it’s not easy to sort out one species.”

A silent public health threat

Despite the public health threat, the city health department offers no help to flood victims.

“We don’t handle mold,” the Chicago Department of Public Health said in a statement.

The department does acknowledge that “mold exposure can result in respiratory issues like sneezing, coughing or wheezing, especially for people who suffer from asthma or allergies.”

Neither the city nor the state health departments have numbers on cases of mold-induced illness.

It’s a public health hazard that’s not officially recognized, other than in public housing. Federal housing authorities provide guidelines for Chicago Housing Authority and other agencies to protect residents from mold.

Doctors may determine their patients have developed health issues from the exposure.

Mold can also be stubbornly hard to remove because it embeds in drywall and other surfaces.

“Three years after, and the mold grows,” says Rubye Bailey, who lives in Austin. She also just had work done to remove mold from her finished basement, which flooded in 2023. “Mold took over.”

One West Side politician notes work needs to be done to prevent this kind of flooding, including improving infrastructure to manage the stormwater.

“More is needed to mitigate these growing environmental challenges and reduce resulting potential health concerns related to basement mold, debris and dirty water,” says Ald. Emma Mitts (37th). “This is an important public health issue.”

In 2023, Mayor Brandon Johnson walked through Austin, his neighborhood, as well as other West Side communities, vowing to help residents. He told them government officials were doing everything they could.

Now, Johnson says help is still on the way. His administration is figuring out how to spend more than $400 million from federal housing officials related to the floods.

"While the pace of change can always be faster,” the mayor said in a statement, “my administration is committed to making sure these dollars get to the people who need them most as efficiently as possible."

This article was produced as a project for USC Annenberg’s Center for Health Journalism and Center for Climate Journalism and Communication 2025 Health and Climate Change Reporting Fellowship.