D. History of the Current Review

The EPA initiated this current review in December 2005 with a call for information (70 

FR 73236) for the development of a revised Integrated Science Assessment for Oxides of 

Nitrogen and Oxides of Sulfur- Ecological Criteria (henceforth the "ISA"). An Integrated 

Review Plan (IRP) was developed to provide the framework and schedule as well as the scope of 

the review and to identify policy-relevant questions to be addressed in the components of the 

review. The IRP was released in 2007 (US EPA, 2007) for CASAC and public review. EPA 

held a workshop in July 2007 on the ISA to obtain broad input from the relevant scientific 

communities. This workshop helped to inform the preparation of the first draft ISA, which was 

released for CASAC and public review in December 2007; a CASAC meeting was held on April 

2-3, 2008 to review the first draft ISA. A second draft ISA was released for CASAC and public 

review in August 2008, and was discussed at a CASAC meeting held on October 1-2, 2008. The 

final ISA (US EPA, 2008) was released in December 2008. 

Based on the science presented in the ISA, EPA developed a Risk and Exposure 

Assessment for Review of the Secondary National Ambient Air Quality Standards for Oxides of 

Nitrogen and Oxides of Sulfur (henceforth the “REA”) to further assess the national impact of 

the effects documented in the ISA. The Draft Scope and Methods Plan for Risk/Exposure 

Assessment: Secondary NAAQS Review for Oxides of Nitrogen and Oxides of Sulfur outlining 

the scope and design of the future REA was prepared for CASAC and public in March 2008. A 

first draft REA was presented to CASAC and the public for review in August 2008 and a second 

draft was presented for review in June 2009. The final REA (US EPA 2009) was released in 

September 2009. A first draft Policy Assessment was released in March 2010 and reviewed by

CASAC on April 1-2, 2010. In a June 22, 2010 letter to the Administrator, CASAC provided 
advice and recommendations to the Agency concerning the first draft Policy Assessment (Russell 

and Samet, 2010a). A second draft Policy Assessment was released to CASAC and the public 

in September 2010 and reviewed by CASAC on October 6-7, 2010. CASAC provided advice 

and recommendations to the Agency regarding the second draft Policy Assessment in a 

December 9, 2010 letter (Russell and Samet 2010b). CASAC and public comments on the 

second draft Policy Assessment were considered by EPA staff in developing a final Policy

Assessment (US EPA, 2011). CASAC requested an additional meeting to provide additional 

advice to the Administrator based on the final Policy Assessment on February 15–16, 2011. 

EPA released on January 14, 2011, the final Policy Assessment prior to final document 

production, to provide sufficient time for CASAC review of the document in advance of this 

meeting. A final Policy Assessment, incorporating final reference checks and document 

formatting, was released in February 2011. In a May 17, 2011 letter (Russell and Samet, 2011a), 

CASAC offered additional advice to the Administrator with regard to recommendations and 

revisions to the secondary NAAQS for oxides of nitrogen and oxides of sulfur. 

On February 3, 2006, the Center for Biological Diversity and four other plaintiffs filed an 

amended complaint alleging that EPA had failed to complete the current review within the period 

provided by statute.1 The schedule for completion of this review is governed by a consent decree 

resolving that lawsuit and the subsequent extension agreed to by the parties. The schedule 

presented in the original consent decree that governs this review, entered by the court on 

November 19, 2007, was revised on October 22, 2009 to allow for a 17 month extension of the 

schedule. The current decree provides that EPA sign for publication notices of proposed and 

final rulemaking concerning its review of the oxides of nitrogen and oxides of sulfur NAAQS no 

later than July 12, 2011 and March 20, 2012, respectively. 

 

1 Center for Biological Diversity, et al. v. Johnson, No. 05–1814 (D.D.C.)
This action presents the Administrator’s proposed decisions on the review of the current 

secondary oxides of nitrogen and oxides of sulfur standards. Throughout this preamble a number 

of conclusions, findings, and determinations proposed by the Administrator are noted. While 

they identify the reasoning that supports this proposal, they are only proposals and are not 

intended to be final or conclusive in nature. The EPA invites general, specific, and/or technical 

comments on all issues involved with this proposal, including all such proposed judgments, 

conclusions, findings, and determinations.