Examining Diesel Risk Reduction Efforts in California - Ten Years After Classification of Diesel Particulate Matter as a Toxic Air Contaminant

摘要

This paper examines the decade-long effort to reduce airborne diesel particulate matter (DPM) since its classification in 1998 as a toxic air containment (TAC) by the State of California. An overview of regulatory actions triggered by the 1998 TAC classification and subsequent issuance of the California Diesel Risk Reduction Plan (DRRP) is provided, along with estimated airborne DPM in the ensuing time period. In addition to the development of control measures aimed specifically at reducing DPM emissions from a variety of emission source categories, there have been other regulatory programs aimed at addressing potential impacts to specific populations from individual sources or projects; namely, permitting programs for new and existing sources, as well as the California Environmental Quality Act (CEQA), which requires environmental reviews as part of the planning and approval of new projects. To assist lead agencies in evaluating the DPM impacts from proposed land use actions under CEQA, guidance documents have been developed by the California Air Resources Board (ARB) and local air pollution control agencies. At the time of this writing, many lead planning agencies are in the process of examining their procedures to incorporate this guidance and arrive at land use decisions that balance project attributes with appropriate DPM health risk mitigations. Case examples on the implementation of this guidance are provided in this paper, along with perspectives on the overall California efforts to reduce DPM exposures and what the future may hold.