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Air Quality Planning for Transportation Officials


Area source
Small, non-transportation pollution sources that are too small and/or numerous to be included as point sources but may collectively contribute significantly to air pollution (e.g., dry cleaners).

Attainment area
An area considered to have air quality that meets or exceeds the U.S. Environmental Protection Agency (EPA) health standards used in the Clean Air Act. Nontattainment areas are areas considered not to have met these standards for designated pollutants. An area may be an attainment area for one pollutant and a nonattainment area for others.

A process to assess the consistency of any transportation plan, program or project with State air quality implementation plans. The transportation conformity process is defined by the Clean Air Act, and implemented by 40 CFR 51 and 93.

Conformity SIP
A State Implementation Plan (SIP) that contains criteria and procedures for DOT, MPOs and other State or local agencies to assess the conformity of transportation plans, programs, and projects, consistent with 40 CFR 93.

Control Strategy SIP
A State Implementation Plan (SIP) that contains specific strategies for controlling the emissions and reducing ambient levels of pollutants in order to satisfy CAA requirements for demonstrations of reasonable further progress and attainment.

Criteria Pollutants
A group of very common air pollutants regulated by EPA on the basis of criteria (information on health and/or environmental effects of pollution). Criteria air pollutants are widely distributed all over the country. The criteria pollutants are ozone, carbon monoxide, nitrogen dioxide, particulate matter, lead, and sulfur dioxide.

Emission Rate Models
Are used to estimate emission rates associated with on-road vehicle activities. Outputs from emission rate models are used as inputs to local dispersion models and regional emission inventory models.

Emissions Inventory
A complete list of sources and amounts of pollutant emissions within a specific geographic area and time interval.

Environmental Protection Agency (EPA)
The Federal regulatory agency responsible for administering and enforcing the Federal environmental laws including the Clean Air Act, the Clean Water Act, and others.

Federal Highway Administration (FHWA)
An agency of the U.S. Department of Transportation that funds highway planning and programs.

Federal Transit Administration (FTA)
An agency of the U.S. Department of Transportation that funds transit planning and programs.

Highway Sanctions
Enforcement tool provided under the Clean Air Act. Prohibits the funding of highway projects in areas that fail to meet certain air quality planning requirments.

Inspection and Maintenance Program (I/M)
An emissions testing and inspection program implemented by States to ensure that the catalytic or other emissions control devices on in-use vehicles are properly maintained.

Maintenance Area
Any geographic region of the United States previously designated nonattainment pursuant to the CAA Amendments of 1990 and subsequently redesignated to attainment subject to the requirement to develop a maintenance plan under section 175A of the CAA, as amended.

Metropolitan Planning Organization (MPO)
The organizational entity designated by Federal law with lead responsibility for developing transportation plans and programs for urbanized areas of 50,000 or more in population.

Mobile source
Mobile sources of pollutants include motor vehicles, aircraft, seagoing vessels, and other transportation modes.

Motor Vehicle Emissions Budget (MVEB)
That portion of the total allowable emissions defined in the applicable State Implementation Plan (SIP), for a certain date for the purpose of meeting reasonable further progress milestones or attainment or maintenance demonstrations for any criteria pollutant or its precursors allocated by the applicable SIP to highway and transit vehicles.

National Ambient Air Quality Standards (NAAQS)
Federal standards that set allowable concentrations and exposure limits for various pollutants. The EPA developed the standards in response to a requirement of the CAA.

National Environmental Policy Act (NEPA)
The National Environmental Policy Act of 1969, as amended (42 USC 4321 et seq.)

Nonattainment Area
A geographic region of the United States that the EPA has designated as not meeting a given national ambient air quality standard (NAAQS).

State Implementation Plan (SIP)
An air quality plan mandated by the CAA and developed by the State that contains procedures to monitor, control, maintain, and enforce compliance with the national ambient air quality standards (NAAQS).

Transportation Control Measures (TCMs)
Actions identified in a SIP to adjust traffic patterns or reduce vehicle use to reduce air pollutant emissions. These may include HOV lanes, provisions of bicycle facilities, ridesharing, telecommuting, etc.

Transportation Improvement Program (TIP)
Also known as a transportation program, a TIP is a program of transportation projects drawn from or consistent with the transportation plan and developed pursuant to Title 23, U.S.C. (United States Code) and the Federal Transit Act.

Transportation Plan
This is a long-range plan that identifies facilities that should function as an integrated transportation system, and developed pursuant to Title 23, U.S.C. (United States Code) and the Federal Transit Act. It gives emphasis to those facilities that serve important national and regional transportation functions, and includes a financial plan that demonstrates how the long-range plan can be implemented.

Updated: 8/4/2015
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