Environmental Progress - Spring 1999

Tailpipes to Treadmills: VIM Tests Moving Ahead

Smog reduction, health protection are among testing program's benefits.

Smoke-belching smokestacks symbolized air pollution when Congress passed the Clean Air Act in 1970, but other sources of air-borne contaminants soon began to generate concern as well. By the mid '80s, federal authorities were demanding that states reduce vehicle emissions in areas where identifiable air quality problems existed. Illinois had two such areas, located in the northeastern and southwestern sections of the state.

Approximately 2.4 million vehicles were scheduled for testing.

In 1986 the Illinois EPA unveiled the Air Team, the Agency's program to reduce motor vehicle emissions of hydrocarbons and carbon monoxide in the metropolitan Chicago area including all of Cook County and parts of DuPage and Lake counties, as well as parts of Madison and St. Clair counties in the St. Louis area. Subsequently, all of DuPage and most of Lake County was included, and parts of Kane and Will counties were added. The newest program changes included all of Lake County, and added parts of McHenry and Kendall counties. In the Metro East St. Louis area, part of Monroe County has been added and more of Madison and St. Clair Counties.

The first test stations were built and operated by a private contractor under a state contract. Currently, the program is operated under a contract with Envirotest Inc. With 52 lanes in 18 centers, in 1986 the Air Team expected to test approximately 2.4 million vehicles yearly and predicted that roughly 85 percent of them would pass.

In the 13 years since the program got underway, the testing program has been credited with reducing ozone-forming hydrocarbon emissions by 11 percent and carbon monoxide emissions by 20 per cent in the Chicago area. In the East St. Louis metropolitan area, where smaller vehicle populations are subject to testing, reductions are estimated at 5 percent for hydrocarbons and 10 percent for carbon monoxide.

Thirty-five stations now provide 139 test lanes.

The program itself has also grown. New stations have been built, older stations have been renovated to accommodate more complex testing equipment, and hours of operation have been expanded in the Chicago area where the bulk of testing occurs. A hotline has been established so motorists can determine "real time" wait times and plan their mandatory visits accordingly. Waiting times are also continuously updated on digital signs at each station.

There are now 35 stations with 139 test lanes.

Over 13 years, auto designs have become more sophisticated, necessitating new technology to accurately measure emissions from the newer vehicles' advanced systems.

Initial tests involved inserting a measuring probe into the tailpipe of a car while its engine idled, a procedure that is still used in testing pre-1981 model year vehicles. For more recent models, an enhanced test is now required that uses a treadmill-like device called a dynamometer to simulate typical city driving.

While drivers remained at the wheel for the idle test procedure, the new test requires drivers and passengers to exit the car. From a nearby glass-walled waiting booth they can observe the test. A certified inspector drives the vehicle onto the testing equipment, the exhaust is captured at varied acceleration and deceleration points, and its contents identified and measured.

If the vehicle fails, the motorist receives a vehicle inspection report and a repair diagnostic report which contains information that will be useful for making required repairs.

All vehicles brought in for emissions testing are also checked to be sure the gas cap is working properly and preventing fuel vapors from escaping into the atmosphere.

The new enhanced testing became mandatory on Feb. 1, 1999. When the program is fully implemented it is expected that carbon monoxide emissions will be reduced by 35 percent and release of hydrocarbons will be cut by 30 percent.

Since vehicles contribute an estimated one-third of the pollutants that cause ground-level ozone, or smog, the reductions should significantly reduce low level ozone incidents. Such ozone is a respiratory irritant that has been linked with health problems, especially among children, the elderly, and those with heart and lung diseases.