The purpose of this e-mail is to convey information on developments in air toxics. In recent months, interest in mobile source air toxics (MSAT) has grown considerably within the transportation-environmental community. Our knowledge and policy experience in dealing with MSAT emissions is growing, but we have a ways to go before we will be able to fill the research gap and establish an adequate level of working capability in this area. The human health impacts of MSAT emissions, the actual composition of these emissions, the transportation contribution in project planning and analysis are but a few of the questions that remain unanswered.

The FHWA is involved in at least one lawsuit where the assessment of MSAT impacts resulting from highway projects is being questioned. The litigation centers on highway improvement projects along US 95 in Las Vegas. Environmental advocacy groups have challenged project sponsors, questioning the treatment of air toxics in the National Environmental Policy Act (NEPA) process. Potential projects are under increased scrutiny elsewhere, most recently centering on plans for a section of I-70 in Denver.

The FHWA is working with EPA counterparts to further our knowledge in this area over the long-term and to develop a policy memorandum and associated guidance in the near term. For your use prior to the completion of these efforts, we have attached our memorandum of February 4, 2002, outlining our approach to the US 95 project; a memorandum of April 3, 2003, transmitting and summarizing research we commissioned to evaluate California's Multiple Air Toxics Emissions Study and its transferability to the US 95 project; and the referenced research.

As we develop policy and guidance to address these emerging issues, we would like to hear of any developments in the States relative to the air toxics issue. Please feel free to consult with Michael Koontz (Michael.Koontz@fhwa.dot.gov, 202-366-2076).