(CBS) — It was a multi-million dollar project, but are sound-proof windows installed around Midway Airport making people sick?

Now, some Chicago aldermen are demanding answers following a report by 2 Investigator Pam Zekman.

It happens when the sun beats down on the windows with frames made of polyvinyl chloride, a known carcinogen.

“It’s like a burning smell,” Donica Bradford, who lives near Midway, has told Zekman. “It’s overpowering at certain times of the day.”

And Bradford says her daughter’s house next door has the same type of windows and the same smell.  The Bradfords are especially concerned about that home because that’s where their 18-month-old grandson, Brayden, lives.

“Safety more than anything for him is the biggest concern for me,” says Brad Bradford, the child’s grandfather.

At a recent Chicago City Council Finance Committee meeting, the Bradfords’ alderman, Marty Quinn, and others demanded answers from Aviation Commissioner Ginger Evans. They want her to testify at an upcoming special joint hearing with the city council aviation committee.

“And we can get to the bottom of what’s causing the odors,” Quinn, who represents the 13th Ward, says.

The city has offered to replace windows with a confirmed smell and test them in a lab, if homeowners sign a settlement agreeing not to sue in the future. But that is unacceptable to many who say they want the air tested in their homes.

Finance Committee Chairman Ed Burke agrees.

“That air should be tested immediately. That’s where people are living, that’s where their kids are sleeping and breathing this air,” the alderman says.

Burke says residents should not be required to sign their rights away, either. “Of course not. That makes no sense.”

On Wednesday, the City Council will vote on the order to call the aviation commissioner before a special hearing.

The windows in question were made by a company called Sound Solutions, which is now out of business.  Its owner denies the windows are causing the smell.

A spokesperson for the Aviation Department says its inspectors have responded quickly to homeowner complaints. The city is “committed” to identifying the cause of the problem and fixing it.

That may include hiring an expert to advise the city on testing protocols, CBS 2 has learned.