Citizens for Appropriate Transportation (CAT)
The Eisenhower Transportation Corridor

EXPRESSWAY AIR POLLUTION – THE AIR WE BREATHE

Because the Eisenhower Expressway carries such a large volume of traffic (about 200,000 vehicles a day), air pollution is a major concern. The Chicago Area Transportation Study (CATS) estimates that the Ike will carry about 270,000 vehicles a day by the Year 2020, a 35 percent increase. Every motor vehicle on the Ike has at least one tailpipe that emits pollution. Health studies conclude that people who live near busy highways tend to get sick more often.

Research by the U.S. Federal Highway Administration concludes that pollution levels caused by motor vehicles are higher somewhere between 1,600 and 3,300 feet away from the roadway depending on weather conditions. This distance is about 4.5 to 9 blocks on either side of the Ike.

The U.S. Environmental Protection Agency designates northeastern Illinois as a severe non-attainment area for ozone pollution and requires this region to come into compliance by 2007.

Ozone pollution occurs when hydrocarbons and nitrogen oxides combine in the presence of sunlight. It is mainly a Summer problem because sunlight affects the photochemical reaction that produces ozone. A thermal inversion can cause smog to increase. A thermal inversion occurs when there is a layer of cool air lying near the ground with a layer of warm air sitting on top of it. The warm air layer acts as a lid over the cool air layer, preventing the dispersion of pollutants.

Ozone is a health problem. Ozone pollution can exacerbate lung and respiratory disorders. People exposed to ozone for a short time period can experience shortness of breadth, coughing, stinging eyes, tightness in the chest, and irritation in the nose and throat. Ozone particularly affects people who exercise outdoors, people with respiratory illness, the elderly, and young children. Ozone and other pollutants make up smog. When high ozone levels occur, people are asked not to drive cars and to avoid participating in active sports.

In urban areas, motor vehicles account for almost half of the nitrogen oxides and hydrocarbons, (the precursors of ozone), and almost 90 percent of the carbon monoxide. Emission levels are directly related to vehicle operating speed. Hydrocarbons and carbon monoxide are higher at slow speeds (especially lower than 20 miles per hour), and they are higher at speeds over 50 to 55 miles per hour.

This is a good news – bad news situation. The good news is that the emissions per motor vehicle are decreasing significantly over time. New cars with emission controls, cleaner and new fuels, and vehicle refueling controls are decreasing the pollution level per vehicle mile of travel. The bad news is that there are more vehicles on the road that travel more miles over time. Older vehicles, poor engine tuning, emission control tampering, and a few “super-dirty” vehicles with improperly operating emission controls increase the pollution in the air.

Carbon monoxide is a colorless, odorless gas. In urban areas, transportation accounts for about two-thirds of all carbon monoxide emissions. When motor vehicle engines are running, they burn fuel that emits carbon monoxide. The amount of carbon monoxide emitted is higher when the fuel-to-air ratio in the engine is higher – something that occurs when a vehicle is started (especially in cold weather with the choke set). The amount of carbon monoxide is also higher when the engine is idling or it is improperly tuned. In high concentrations, carbon monoxide is deadly. People with heart disease, anemia or other blood disorders, and people with chronic lung disease are most at risk. Carbon monoxide is mostly a Winter problem because of engine cold starts.

Particulates are small pieces of grit that mostly come from exhaust emissions, but some come from vehicle brakes and tires. Fine particulates can be suspended in the air for days or weeks and humans can breathe them deeply into their lungs. Large particulates tend to fall to the ground quickly. When humans breathe them in, they usually are trapped in the upper respiratory system. Engines that burn unleaded gasoline and have a catalytic converter mostly trap particulates. People with asthma are most affected by particulates.

Nitrogen Oxides are released into the air from fuel combustion. Nitrogen oxides react with Volatile Organic Compounds when heat and sunlight are present to form ozone. The reaction rate depends on the intensity of heat and sunlight, which explains why ozone is mostly a Summer problem. Nitrogen oxides can cause upper respiratory irritation and lower human resistance to pneumonia.

Sulfur Dioxide is more an issue with diesel engines than it is with gasoline engines. Sulfur dioxide is an irritant to people with asthma and it has an unpleasant smell.

IDOT should do a detailed air pollution analysis for all of the viable alternatives, not just HOV lanes. An air pollution analysis estimates air pollution levels at locations where people are, such as houses and apartments, schools (Ascension, Garfield, Irving, Lincoln, and Longfellow), churches, Maze Branch Library, the South Oak Park Fire Station, Conservatory, parks (Barrie, Rehm, and Veterans Park, for example), and the South Oak Park Post Office.

IDOT needs to answer a critical question. Will adding HOV lanes make the health risk greater and if so, by how much?

Rick Kuner - August 2002

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