A Guide to Understanding Air Quality

Air Quality

The quality of air has a direct effect on human health as well as the environment. The federal government through the U.S. Environmental Protection Agency (EPA) has set standards called National Ambient Air Quality Standards (NAAQS) for various components found in the air to ensure that the air will be healthy.

Air Pollution is generated mainly from two sources:

mobile (Vehicles)
stationary (Natural or Man-generated)

The Connecticut Department of Transportation’s (CTDOT) main concern is with pollutants related to mobile sources. These include ozone, carbon monoxide, volatile organic compounds, nitrogen oxides, particulate matter and sulfur dioxides.

Air quality emission levels are measured by the Department of Environmental Protection (DEP) with monitors at various sites throughout the state. In addition, advanced computer models are used to determine if implementing a transportation project would negatively impact the environment in the future. No new project can be built that would cause an increase of pollution or delay attainment of the NAAQS, without mitigation.

MOBILE EMISSIONS LAWS/REGULATIONS

The Clean Air Act Amendments (CAAA) were enacted with the power to penalize states by taking Federal transportation monies away from projects if air quality standards are not met. Title I of the CAAA defines mobile sources as motor vehicles, aircraft, seagoing vessels and other transportation modes. EPA sets non-attainment designation for geographic areas throughout the United States.

The State must formulate, conform and implement a State Implementation Plan (SIP) to deal with the goal of obtaining NAAQS. Transportation projects must conform to the submitted and approved SIP.

The National Environmental Policy Act also requires documentation and procedures to ensure protection of the environment, including air quality.

The DEP requires that an Indirect Source Permit be submitted for specific types of projects such as new roadways. DEP then evaluates the air quality impacts related to that transportation project and issues a permit if it meets the NAAQS and incorporates mitigation measures that may be required.

August 1998

Connecticut Department of Transportation
Office of Environmental Planning
2800 Berlin Turnpike
PO Box 317546
Newington, CT 06131-7546