The U.S. Environmental Protection Agency (EPA) is conducting a review of the existing air quality criteria for particulate matter (PM) and of the primary (health-based) and secondary (welfare-based) national ambient air quality standards (NAAQS) for PM. This review will provide an integrative assessment of relevant scientific information on PM and will focus on the basic elements of the PM NAAQS: the indicator, averaging time, form, and level. These elements, which together serve to define each NAAQS, are considered collectively in evaluating the protection to public health and public welfare afforded by the standards. The purpose of this Integrated Review Plan (IRP) is to communicate the plan for reviewing the air quality criteria and the primary and secondary NAAQS for PM. The Clean Air Scientific Advisory Committee (CASAC), an independent scientific advisory committee established under the Clean Air Act (CAA), reviewed a draft of the IRP at public teleconference meetings held on May 23, 2016 and August 9, 2016. The CASAC provided its advice on the draft IRP to the Administrator in a letter dated August 31, 2016 (Diez Roux, 2016). This final IRP reflects the EPA staffÃ¢â‚¬â„¢s consideration of the CASACÃ¢â‚¬â„¢s advice and of comments received from members of the public. As this review progresses, the plan described in this IRP may be modified to reflect information received during the review process, to address additional advice received from the CASAC, and/or to address comments received from the public.