Transportation Conformity

The U.S. Environmental Protection Agency (USEPA) defines Transportation Conformity as a bridge which connects air quality and transportation planning activities.

The Clean Air Act Amendments of 1990 (CAAA) require the USEPA to establish National Ambient Air Quality Standards (NAAQS) for various air pollutants. Areas where air quality monitoring shows a violation of the NAAQS are designated “non-attainment.”  By law, the New York State Department of Environmental Conservation (NYSDEC) is required to produce a State Implementation Plan (SIP) that details how the NAAQS will be achieved in a specific non-attainment area.

Non-attainment areas are subject to a requirement known as Transportation Conformity.The intent of Transportation Conformity is to fully coordinate transportation and air quality planning to ensure that the Regional Transportation Plan (the Plan) and the Transportation Improvement Program (TIP) projects which are analyzed will not 1) cause or contribute to any new violation of the NAAQS, 2) increase the frequency or severity of any existing NAAQS violations, or 3) delay timely attainment of the NAAQS or any required interim emissions reductions or other milestones in any area. The NYMTC Transportation Conformity Determination quantitatively demonstrates how the NYMTC Plan and TIP projects impact future mobile source emissions milestones set in the relevant SIPs.


NYMTC Planning Area Boundaries

The NYMTC Transportation Conformity Determination addresses all pollutant non-attainment areas that fall in whole or in part within the NYMTC Planning Area Boundary. These include the following:

  • The New York Metropolitan Eight-Hour Ozone Moderate Non-Attainment Area consisting of all NYMTC counties except for Putnam County.
  • The Carbon Monoxide (CO) Maintenance Area consisting of New York City (New York, Kings, Queens, Bronx and Richmond counties), Nassau and Westchester counties.
  • The Coarse Particulate Matter (PM10) Non-Attainment Area is limited to the county of New York.
  • The New York-New Jersey-Connecticut Annual and 24-Hour Fine Particulate Matter (PM 2.5) Non-Attainment Area includes all NYMTC counties except Putnam and includes all or portions of eight other MPO boundaries in the tri-state area. Coordination between NYMTC and OCTC analysis is required to show compliance with the NYS PM2.5 SIP.

For more information contact Gerry Bogacz