Programs >> Air Quality Planning

The 1990 Clean Air Act Amendments (CAAA), the Intermodal Surface Transportation Efficiency Act (ISTEA) and its successor, TEA-21, have renewed emphasis on transportation policies, strategies and projects that will reduce vehicular emissions and support attainment of national air quality standards.

Northeastern Illinois does not attain national ambient air quality standards for certain pollutants. It is classified as a moderate non-attainment area for the 8-hour ozone standard, and a non-attainment area for the annual fine particulate matter (PM2.5) standard. It must implement a transportation program which will help to reduce levels of these pollutants to national standards by 2010.

On-road motor vehicles account for about 28% of the emissions of volatile organic compounds (VOCs) and about 44% of nitrogen oxides (NOx), which contribute to high levels of ground-level ozone. Further information about ozone and its effects can be found at the U.S. Environmental Protection Agency web site at http://www.epa.gov/airnow/health/smog.pdf.

On-road motor vehicles also account for about 13% of PM2.5 emissions. For further information about PM2.5 and its effects, view the CATS presentation, Particulate Matter (PM) in Northeastern Illinois, or go to the U.S. Environmental Protection Agency web site at http://cfpub.epa.gov/airnow/index.cfm?action=particle.cover.

Much of the air quality improvement since 1990 is due to vehicle and fuel technology improvements. However, transportation projects to reduce congestion, increase transit, bicycle and pedestrian travel, and manage demand play an important role in achieving the national standards.

CATS works with the Ilinois Environmental Protection Agency (IEPA) Ilinois Environmental Protection Agency (IEPA) to identify the region’s transportation emissions targets. These targets are identified in a State Implementation Plan (SIP) as vehicle emissions “budgets.” In addition to the budgets, the SIP also identifies specific actions to reduce emissions. These actions are called Transportation Control Measures (TCMs).

In 1994, CATS established the Transportation Control Measures Development Task Force to identify and evaluate a mix of strategies to incorporate into the SIP. These strategies included traditional facility improvements such as transit vehicle and station rehabilitation, commuter parking lot expansion, traffic signal coordination, pedestrian and bicycle facility improvements. They also included market-based and innovative strategies such as demand management, pricing incentives, and preferential treatment for high-occupancy vehicles. The Task Force identified TCMs producing four tons per day of emissions reductions; credit for this emission reduction is included in the SIP.

Although further TCMs are not needed to achieve the region’s air quality goals, CATS continues to identify projects with air quality benefits through its Air Quality and Transportation Management Task Force.

As part of the transportation planning and programming process, CATS staff evaluates the impact of proposed transportation activities on the region’s air quality. This evaluation, called a conformity analysis, is submitted to the Illinois Environmental Protection Agency and U.S. Environmental Protection Agency for their review before a long-range regional transportation plan or Transportation Improvement Program (TIP) is approved. The conformity analysis must demonstrate that the emissions resulting from the plan or TIP meet the requirements of (“conform with”) the regulations governing air quality. To see the current conformity analysis, click here.