Residents near Chicago’s two airports and their aldermen are putting pressure on city officials to find out why soundproof windows smell on hot days. More and more homeowners are complaining that the windows they got through a city sound proofing program sometimes smell like burnt plastic. The city found 250 homes with problem windows and have done air quality testing in nine of them. On Monday, aldermen advanced a pair of ordinances to require air testing in 16 more homes and provide relief to homeowners whose windows are no longer under warranty.