Transportation conformity is required under the Clean Air Act (CAA) Section 176(c) to ensure that Federally-supported transportation activities are consistent with (“conform to”) the purpose of a State Implementation Plan (SIP). Transportation conformity establishes the framework for improving air quality to protect public health and the environment. Conformity to the purpose of the SIP means Federal Highway Administration (FHWA) and Federal Transit Administration (FTA) funding and approvals are given to highway and transit activities that will not cause new air quality violations, worsen existing air quality violations, or delay timely attainment of the relevant air quality standard, or any interim milestone. This Guide was prepared to help State and local officials understand transportation conformity and how conformity requirements relate to transportation investments in their communities. Specifically, the implications of conformity on metropolitan transportation plans, transportation improvement programs (TIPs), and transportation projects are discussed. The Guide provides overview information on the major elements of the conformity process and provides answers to basic questions. Several exhibits are included in the Guide to illustrate key elements of the conformity process. Appendices are also included that discuss the health effects of pollutants, options to reduce on-road mobile source emissions, and resource agency contacts.

Managing the nation's air quality is a complex undertaking, involving tens of thousands of people in regulating thousands of pollution sources. The authors identify what has worked and what has not, and they offer wide-ranging recommendations for setting future priorities, making difficult choices, and increasing innovation. This new book explores how to better integrate scientific advances and new technologies into the air quality management system. The volume reviews the three-decade history of governmental efforts toward cleaner air, discussing how air quality standards are set and results measured, the design and implementation of control strategies, regulatory processes and procedures, special issues with mobile pollution sources, and more. The book looks at efforts to spur social and behavioral changes that affect air quality, the effectiveness of market-based instruments for air quality regulation, and many other aspects of the issue. Rich in technical detail, this book will be of interest to all those engaged in air quality management: scientists, engineers, industrial managers, law makers, regulators, health officials, clean-air advocates, and concerned citizens.