The first was a study of soot deposits found in the area near O’Hare conducted 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. 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 truck and car traffic, industrial and manufacturing 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 – "Advanced Chemical Fingerprinting" – 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 indicates 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 purposes were to better understand 1) the relative contribution of aircraft using O’Hare to air quality in the areas immediately surrounding the airport and 2) the progress that has been made in reducing aircraft emissions from aircraft using O’Hare. The substances evaluated were total VOCs; benzene; 1,3-butadiene; formaldehyde; and POMs.

The findings include these results:

• Aircraft emitted only 1.6% of VOCs in and around O’Hare.
• Aircraft emitted less than 2.5% of local benzene, less than 12% of the 1,3-butadiene and less than 21% of the formaldehyde.
• 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.
• Home furnaces emitted more benzene in neighborhoods near O’Hare than aircraft.
• Motor vehicles in communities near O’Hare emitted over 75 times the quantity of the POMs with suspected significant health effects than aircraft using the airport.
• Total VOC 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.

Together, these findings indicate that aircraft using O’Hare play only a minor role in regional ozone formation and contributions to "air toxics" emissions near the airport. These results are consistent with recent findings by the Illinois EPA that the area around O’Hare experienced "air toxics" and pollution levels that are "similar to the concentrations in other parts of Chicago and other urban areas".

Commissioner Walker said that the airport and its airline tenants have worked hard to minimize negative environmental impact at O’Hare. Current initiatives 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. Commissioner Walker stated that, "We can always do more and we will do more." Walker added, "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 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."