US EPA

EPA is in the process of updating and revising, where appropriate, its Air Quality Criteria for Particulate Matter as issued in 1996 (usually referred to as the Criteria Document). Sections 108 and 109 of the Clean Air Act require that EPA carry out a periodic review and revision, where appropriate, of the air quality criteria (embodied in the Criteria Document) and national ambient air quality standards (NAAQS) for criteria air pollutants such as PM. Details of EPA's plans for the review of the NAAQS for PM were initially announced in a previous Federal Register notice (62 FR 55201, October 23, 1997). EPA made a First External Review Draft of the updated Air Quality Criteria for Particulate Matter available for review by the Clean Air Act Scientific Advisory Committee (CASAC) and members of the public in October 1999 (64 FR 57884, October 27, 1999). Following that public review period and a meeting of the CASAC in December 1999 (64 FR 61875, November 15, 1999), EPA revised the document as appropriate to incorporate CASAC and public comments, as well as to reflect many new studies on the effects of PM that were not available in time for discussion in the First External Review Draft.

EPA then made a Second External Review Draft of the Air Quality Criteria for Particulate Matter available for CASAC and public review in April 2001 (66 FR 18929, April 12, 2001). Following that public review period and a second CASAC meeting in July 2001 (66 FR 34924, July 2, 2001), EPA again revised the document as appropriate to incorporate changes in response to CASAC and public comments and also made further revisions reflecting new studies on effects of particulate matter that had become available between issuance of the First and Second External Review Drafts.

EPA then made a Third External Review Draft of the Air Quality Criteria for Particulate Matter available for CASAC and public review in May 2002 (67 FR 31303, May 9, 2002). Following that public review period and a third CASAC meeting in July 2002 (67 FR 41723, June 19, 2002), EPA again revised the document as appropriate to incorporate revisions in response to CASAC and public comments and also made further revisions reflecting new studies on effects of particulate matter that had become available between issuance of the Second and Third External Review Drafts, as well as reanalyses of certain existing studies occasioned after discovery of problems with applications of statistical software.

EPA made a Fourth External Review Draft available for CASAC and public review in June 2003 (68 FR 36985). A public meeting with CASAC was held August 25-26, 2003, during which CASAC reached closure on Chapters 1,2,3,4,5, and 6, with only relatively minor final revisions to be made. No further public review is requested on these chapters. However, CASAC did not reach closure on Chapters 7 (toxicology), 8 (human health), and 9 (integrative synthesis), each of which are to be more extensively revised or, in the case of chapter 9, to be significantly restructured.

EPA is now making revised drafts of Chapters 7 and 8 available for CASAC and public review. These two revised draft chapters will be reviewed by CASAC via a publically accessible teleconference call in late January, 2004 (date and time to be announced in a subsequent Federal Register notice). Following that CASAC teleconference, Chapter 9 will be released for CASAC and public review at a public meeting in early March (date and site to be announced in a later Federal Register notice).

For technical questions only, contact Dennis Kotchmar.

All other questions should be directed to the contact listed above.