As we have discovered, this is not always the case. In areas with poor air quality, the question of how to improve traffic flow in a way that will not exacerbate air pollution must be faced head-on. Conformity requires state and local governments and the public to consider the air quality impacts of the planned transportation system as a whole and over the long term before transportation plans and projects are implemented. Billions of dollars every year are spent on developing and maintaining our transportation systems. Conformity helps ensure that these dollars are not spent in a way that makes air quality worse.
Conformity requires areas to consider the impacts of their decisions up front.
Though conformity was included in the 1977 Clean Air Act, it wasn't clearly defined until the 1990 Clean Air Act amendments. The amendments strengthened and clarified the conformity requirement and delegated to the Administrator of EPA the responsibility for writing a regulation to establish the criteria and procedures for conformity. We published the first rule in November of 1993. We streamlined and clarified rule in August 1997, based on extensive discussions with state and local air pollution officials, transportation planners, and other stakeholders, as well as the experience of both DOT and EPA employees in the field. To date, we believe conformity has been successful in preventing transportation planning decisions from contributing to new violations.