Under State and federal law, owners and operators of motor vehicles that are licensed from addresses located in so-called “non-attainment” areas must submit their vehicles to automatic vehicle re-inspections. Most large U.S. urban areas, including greater Chicago and greater St. Louis, are non-attainment areas. The presence in the air of significant products of internal combustion engines – typically ozone – is enough to get a region designated as a non-compliant metropolitan area. Vehicles that fail their emissions inspections must get repaired and re-tested. Presentation of an Illinois emissions pass is required as a condition of renewing a stickered Illinois motor vehicle license plate and being allowed to use the vehicle. Read more.