Regulatory Impact Analysis for the Review of the Particulate Matter National Ambient Air Quality Standards

On October 6, 2006, EPA released the Regulatory Impact Analysis (RIA) for the revised particulate matter national ambient air quality standards. This RIA provides EPA's estimates of the range of the monetized human health benefits, control costs, and net benefits associated with meeting the revised suite of standards for fine particles (PM<INF>2.5</INF>) that are published elsewhere in this issue of the Federal Register, as well as for meeting a more stringent alternative. The final rule established a 24-hour standard of 35 g/ m<SUP>3</SUP> and retained the annual standard of 15 g/m<SUP>3</SUP>. The EPA also promulgated a final decision to retain the current 24-hour PM<INF>10</INF> standards and to revoke the current annual PM<INF>10</INF> standards, in order to maintain protection against the health and welfare effects of thoracic coarse particles (PM<INF>10-2.5</INF>). Data and modeling limitations preclude EPA from assessing the costs and benefits of retaining the existing PM<INF>10</INF> 24-hour standard.