Under federal and state regulations, the PSRC is required to demonstrate that the long-range metropolitan transportation plan, Transportation 2040, and the Transportation Improvement Program conform to the State Implementation Plan (SIP) for Air Quality. Required under the federal Clean Air Act, the SIP provides a blueprint of how maintenance and nonattainment areas such as the central Puget Sound region will meet or maintain the National Ambient Air Quality Standards (NAAQS). Positive conformity findings will allow the region to proceed with implementation of transportation projects in a timely manner.

What’s New

Final Guidance on the CMAQ Program (November 2008)
EPA finalizes revisions to the PM2.5 Standard.
Ultra Low Sulfur Diesel available to consumers.

Frequently Asked Questions

• What is conformity?
  • Transportation conformity is a mechanism for ensuring that transportation activities — plans, programs and projects — are reviewed and evaluated for their impacts on air quality prior to funding or approval. The intent of transportation conformity is to ensure that new projects, programs and plans do not impede an area from meeting and maintaining air quality standards. Specifically, regional transportation plans, improvement programs and projects may not cause or contribute to new violations, exacerbate existing violations, or interfere with the timely attainment of air quality standards or the required interim emissions reductions towards attainment. Meeting conformity requirements takes the collective participation of all jurisdictions and agencies that implement transportation projects and programs within the central Puget Sound region.
• What are “nonattainment” and “maintenance” areas?
  • A nonattainment area is an area that does not meet the National Ambient Air Quality Standard (NAAQS) for a given pollutant. A maintenance area is an area that was previously nonattainment but which has since attained the standard, as demonstrated through continued air quality monitoring.There are six pollutants for which NAAQS have been established: ozone (1-hour and 8-hour standards), carbon monoxide, nitrogen dioxide, sulfur dioxide, particulate matter (less than 10 microns in diameter [PM10] and less than 2.5 microns in diameter PM2.5]) and lead. The Central Puget Sound region is currently designated a maintenance area for carbon monoxide and PM10, and is in attainment for all other standards.
• What is the difference between regional conformity and project-level (or hot-spot) conformity?
  • Regional conformity analyses of Destination 2030 and the TIP must demonstrate that the total regional emissions produced by activity on the existing travel network plus current and future projects and programs do not exceed the motor vehicle emissions budget identified in the SIP for each criteria pollutant. The emissions budget is a ceiling of total emissions that cannot be exceeded. Regional conformity analyses are performed by the Regional Council and are based on the U.S. EPA’s approved vehicle emission modeling software (currently MOBILE6.2). Project- level conformity analyses must be conducted for all nonexempt transportation projects located in carbon monoxide and PM10 nonattainment or maintenance areas. Project-level conformity is performed by the project sponsor as part of the project’s environmental review process. Project-level, or ‘hot-spot,’ analyses assess the localized impacts of individual projects and compare them to the NAAQS, using an air quality dispersion model (generally CAL3QHC). Inclusion of a project in the regional conformity analysis does not satisfy project-level conformity requirements. The Guidebook for Conformity: Air Quality Analysis Assistance for Nonattainment Areas contains additional information on project-level conformity, including a list of exempt projects.
• What is Consultation?
  • The consultation process is used to review methodologies and inputs for both regional and project-level conformity analyses, and is required under federal and state conformity regulations. The consultation partners in the Puget Sound region include the US Environmental Protection Agency, Federal Highway Administration, Federal Transit Administration, Washington State Department of Ecology, Washington State Department of Transportation, Puget Sound Clean Air Agency, and the Puget Sound Regional Council.