Two recent air quality studies indicate that aircraft using O'Hare play only a minor role in air pollution near the airport. These results are consistent with recent findings by the Illinois EPA that the area around O'Hare experienced pollution levels that are "similar to the concentrations in other parts of Chicago and other urban areas". These studies were performed by KM Chng Environmental Inc. of Burlington, Massachusetts, a nationally known firm that has been involved in the calculation of aircraft emissions at airports and emissions from many other facilities around the country.

"We are very pleased with these results," said Aviation Commissioner Thomas R. Walker. "It means that the Department of Aviation and the airlines serving O'Hare have had an impact with environmental practices designed to make the airport as 'green' as possible." These practices include the use of alternate fuels for ground vehicles, improved auto traffic flow to reduce idling, the use of more environmentally friendly de-icing chemicals and a new water treatment project for run-off. Seventy-five percent of gates also provide power, air conditioning, and heating to aircraft to reduce the need for aircraft to idle on the ground.

The first study looked at soot deposits found in the area near O'Hare. Any area with significant industrial activity or automotive traffic will have soot in the air. The purpose of this study was to determine if soot deposited near O'Hare came from aircraft operations or from typical urban activities such as traffic, industrial operations, etc. Glass plates were used to collect soot deposits at six locations near O'Hare, some near the ends of runways, and some in nearby communities.

A sophisticated analytical technique was used to analyze the deposits and determine their origins. The results showed that soot near O'Hare did not chemically resemble jet fuel or jet engine exhaust, but were more closely related to general urban pollutants, motor vehicle exhaust, and soot from burning heavier fuels, such as fuel oil. This shows that the components of the soot samples collected are more the result of regional background pollution than jet fuel or aircraft engine exhaust.

For the second study, the City asked KM Chng Environmental Inc. to develop estimates of airport and non-airport emissions, using techniques and models approved by the U.S. EPA and the FAA. The study found that aircraft using O'Hare contribute only a small percentage of total regional air emissions. Off-airport motor vehicles were the number one source of emissions of all the substances studied. For example, motor vehicles emitted over 20 times the amount of benzene as aircraft. Total volatile organic carbon emissions from aircraft using O'Hare during 1998 were 33% lower than IEPA estimates of 1990 O'Hare aircraft emissions. A similar decrease in the emissions of individual air toxics is expected.

Commissioner Walker added, "We can always do more and we will do more. The City and the Department of Aviation will continue to work with the airlines and all of the airport's tenants to address environmental concerns on an on-going basis and strive to make O'Hare not just the greatest, but also the cleanest, airport in the world. The World Gateway Program is designed to help us achieve that goal, for example, by further reducing the amount of time that aircraft spend idling on the ground."