Air Quality

Enhancing air quality to improve quality of life

Regional air quality affects our health, economy, and environment. Northeastern Illinois is in nonattainment with federal standards, meaning that air pollution levels do not meet Clean Air Act standards intended to protect human health. Air quality in northeastern Illinois has improved over the last few decades, but ozone and particulate matter still pose a serious public health threat.

The quality of the air is arguably one of the most important components of life. Air pollution can hinder normal activity and cause severe health impairment; it can damage trees, crops, and other plants and animals; it can impact water quality and obstruct views. Regulations governing air quality play a role in where industries locate, how much energy is used, and how we travel.Air quality issues cross jurisdictional boundaries, within the northeastern Illinois region and with our neighboring states and countries, requiring intergovernmental coordination.

As the region’s metropolitan planning organization (MPO) the Chicago Metropolitan Agency for Planning (CMAP) is responsible for ensuring that transportation investments will not worsen air quality over time. CMAP also programs federal funding to invest in transportation projects that reduce emissions and improve air quality, such as public transit, cleaner trains, bike paths, and sidewalks.

Air pollutants threatening our region

Northeastern Illinois is in nonattainment for ground-level ozone and is expected soon to be in nonattainment for fine particulate matter. This means that air pollution levels do not meet Clean Air Act standards intended to protect human health.

Ozone

Ozone forms when other pollutants, such as emissions from cars, trucks, power plants, and forest fires, react with heat and sunlight. Ozone can damage the lungs, aggravate chronic respiratory problems like asthma, and compromise the body’s ability to fight respiratory infections. Even relatively low exposure can cause chest pain, coughing, shortness of breath, and throat irritation.

Northeastern Illinois does not attain National Ambient Air Quality Standards (NAAQS) for ozone. Depending on the standard it is classified either as marginal or serious nonattainment area for the 8-hour ozone standard.

Particulate matter

Particulate matter includes dirt, dust, soot, and smoke. It comes from many different sources, including power plants, industry, and vehicles. Particulate matter is so small that humans can inhale it, and particles less than 10 micrometers in diameter can get deep into the lungs or even bloodstream. Of particular concern is fine particulate matter less than 2.5 micrometers in diameter (PM2.5).

Equity

While poor air quality affects the entire region, some people are more at risk, such as those with asthma, seniors, children, people with low income, and those in close proximity to emissions sources. High ozone exposure for children can lead to increased cases of asthma when they become adults. People with low income, who may not have good home ventilation and air conditioning, may spend more time outside on days when ozone and PM2.5 levels are higher, increasing their exposure.

Air quality conformity analysis

Because northeastern Illinois is in nonattainment for ozone, the region must implement a transportation program to reach national air quality standards. As part of the transportation planning and programming process, CMAP must demonstrate that emissions resulting from the long-range regional transportation plan and Transportation Improvement Program (TIP) meet (or “conform to”) air quality requirements before they can be approved.

Interagency consultation is an important, and required, part of this conformity analysis. In the northeastern Illinois region, this happens through Tier II Consultation. Decisions made through the consultation process guide the MPO in making conformity determinations.

The current conformity analysis, covering ON TO 2050 and FFY 2023 – 2028 Transportation Improvement Program, includes three documents:

The conformity analysis is updated semi-annually. The eTIP website includes the conformity amendments, the list of currently conformed projects, and approvals by CMAP and state and federal agencies. Read the semi-annual conformity analysis policy and learn more in the conformity frequently asked questions.

Funding and technical assistance

Communities can reduce air pollution by supporting public transit, biking, walking, and electric vehicles. CMAP provides funding for these kinds of activities through the Congestion Mitigation and Air Quality Improvement Program and Transportation Alternatives Program. Through the technical assistance program, CMAP offers planning support for bike and pedestrian plans to help communities increase those forms of transportation.