Environmental Progress - Spring 1998

Enhanced Vehicle Testing Near for Chicago, East St. Louis Areas

Goal is better identification of polluting vehicles.

By early 1991, vehicles in northeastern Illinois and the East St. Louis area will be contributing more to cleaner air. The Illinois EPA’s vehicle emissions test program is in the initial stages of enhancing its program to more effectively identify vehicles that emit excessive pollution.

Since the program began in 1986, more than 25 million tests have been conducted on vehicles in the Chicago and East St. Louis metropolitan areas for emissions of hydrocarbons that form ground-level ozone (smog) and carbon monoxide (CO) that can be harmful to human health.

A 1994 Illinois EPA study showed the existing program has reduced Chicago area hydrocarbon emissions by 11 percent and CO emissions by 23 percent. East St. Louis-area hydrocarbon emissions were reduced by 5 percent, and CO emissions were reduced by 10 percent (reductions in the East St. Louis area are lower due to the smaller vehicle population subject to testing).

However, high concentrations of ground-level ozone persist in Illinois’ urban areas. The 1990 Clean Air Act Amendments require enhanced programs in cities that continue to exceed the federal ozone health standard.

Current testing procedure is effective for pre-1981 model-year vehicles with carburetors, but new technology is necessary to test newer vehicles’ advanced emission-control systems.

Major changes to the test program include:

• Using a treadmill-like device called a dynamometer to simulate typical city driving. The vehicle’s exhaust is captured and its emission contents are identified and measured at different acceleration and deceleration points.

• Testing a vehicle’s gas cap to ensure it will prevent fuel vapors from escaping into the atmosphere. A gas-cap pressure test in use now is only advisory. Vehicles will be required to pass the pressure test when gas cap pressure standards are adopted by the Illinois Pollution Control Board.

• Vehicles will be tested every other year beginning when the car is four model-years old. For example, a 1996 vehicle will be tested in 2000, 2002, 2004, etc.

Expanded areas include 22 new zip code areas in the Chicago metropolitan area and 16 in the East St. Louis metropolitan area.

Additional testing stations will be built to accommodate the increased number of vehicles to be tested and the additional time required to perform the test.

Related links:

• Vehicle Emissions Testing in Illinois