	Introduction

Decisions in July 1997 by the Administrator of the Environmental Protection Agency (EPA) to revise the national ambient air quality standards (NAAQS) for ozone and particulate matter (PM) refocused attention on the criteria and the process by which these decisions are made. These issues were the subject of numerous oversight hearings as well as litigation, which culminated in a Supreme Court ruling February 27, 2001. The court upheld those NAAQS setting procedures at question, in particular definitively rejecting the consideration of costs in setting NAAQS. However, the court's ruling also raised questions concerning the implementation of the EPA's new ozone standard. With the court's decision, continuing controversy over the PM and ozone standards, along with other concerns about the Clean Air Act (CAA), the expiration in 1998 of the authorizations for appropriations in the statute, and the Bush Administration's air quality initiative that would amend the Act, it is possible that the Congress may take up amendments to the CAA. If so, the NAAQS decisionmaking process may command attention, especially with respect to how scientific evidence is used – and possibly reopening the question of whether costs should be considered in setting NAAQS. Because of discrepancies in views on what transpired—or should have transpired—in EPA's development of the 1997 ozone and PM standards, this report provides background on the processes and procedures for setting and revising NAAQS. The 1977 amendments formally established the Clean Air Scientific Advisory Committee (CASAC) and the 5-year review process. The Act provides for "primary standards" to protect health with a margin of safety and for "secondary standards" to protect welfare. Also, the federal government continues to prepare "guidance documents" spelling out available control measures for the NAAQS pollutants. The CAA is quite specific on certain steps of the process: in particular, on the preparation of a "criteria document" summarizing the scientific information, on the review of that document by an independent scientific committee, on the criteria to be used by the Administrator in deciding on the final standard, and on the procedural process for promulgating the standard. In addition, EPA has administratively added a key step, the preparation of a "staff paper" that summarizes the criteria document and lays out policy options; and Executive Order 12866 requires a Regulatory Impact Analysis (RIA), although the economic analysis it contains is legally irrelevant to the actual decision on the standard. This document is not required by the CAA; it is an administrative step designed to facilitate the EPA Administrator's decision. Like the criteria document, the staff paper is reviewed by the scientific advisory committee. In using this language in amending the act, as discussed in the report on the bill, the Committee intended—
(1) To emphasize the preventative or precautionary nature of the act, i.e., to assure that regulatory action can effectively prevent harm before it occurs ...;
(2) To authorize the Administrator to weigh risks and make reasonable projections of future trends ...;
(3) To assure consideration of the cumulative impact of all sources of a pollutant in setting ambient and emission standards, not just the extent of the risk from the emissions from a single source or class of sources of the pollutant; ...
(4) To provide the same standard of proof for regulation of any air pollutant ...;
(5) To assure that the health of susceptible individuals, as well as healthy adults, will be encompassed in the term ' public health, ' regardless of the section of the act under which the Administrator proceeds; and
(6) To reflect awareness of the uncertainties and limitations in the data which will be available to the Administrator in the foreseeable future to enable him to execute his rulemaking duties under this act, because of the limitations on research resources and the fact that decisionmaking about the risks to public health from air pollution falls on ' the frontiers of scientific and medical knowledge. ' The NAAQS-Setting Process
Appendix B.
The decisions by the Administrator of the Environmental Protection Agency (EPA) in July 1997 to revise ambient air quality standards (NAAQS) for ozone and particulate matter refocused attention on the criteria and the process by which these decisions are made. The new standards were the subject of numerous oversight hearings as well as litigation, which culminated in a Supreme Court ruling February 27, 2001. The court upheld the NAAQS-setting procedures at question, in particular definitively rejecting the consideration of costs in setting NAAQS.
However, the court's ruling also raised questions concerning the implementation of the EPA's new ozone standard. With continuing controversy over the PM and ozone standards, along with other concerns about the Clean Air Act (CAA), the expiration in 1998 of the authorizations for appropriations in the statute, and the Bush Administration's proposal for amendments, it is possible that the Congress may take up amendments to the CAA. If so, the NAAQS decisionmaking process may command attention, especially with respect to how scientific evidence is used. Because of the role NAAQS might play in bringing amendments onto the legislative agenda, this report provides background on the processes and procedures for setting and revising NAAQS. The basic steps are as follows:
EPA identifies a pollutant that is emitted from numerous or diverse mobile or stationary sources and that endangers public health or welfare. EPA prepares a "criteria document" that summarizes the scientific information relevant to the pollutant; this document is formally reviewed by a Clean Air Scientific Advisory Committee (CASAC). EPA prepares a "staff paper" that summarizes the criteria document and lays out policy options for the Administrator; it is also reviewed by CASAC. Based on the criteria document, the staff paper, and CASAC's "closure letters," the Administrator proposes a NAAQS; this proposal is published in the Federal Register, a "docket" created, and an opportunity for public review and comment provided. And, The Administrator's final decision, "which, in the judgment of the Admin-istrator, ... [is] requisite to protect the public health ... or public welfare."
The CAA spells out requirements for the criteria document, the CASAC review, the basis on which the Administrator chooses the standard, and the procedural process for promulgating the standard. EPA administratively added the preparation of a "staff paper"; in addition, Executive Order 12866 requires a Regulatory Impact Analysis (RIA), although the economic analysis is essentially irrelevant to the decision a NAAQS. Other laws also raise regulatory assessment issues. The Act requires EPA to revisit each NAAQS every 5 years, following the same process.
Several aspects in the NAAQS-setting process have been the foci of attention in the past and might be revisited: these include the Act's requirement that NAAQS be set to protect health with an adequate margin of safety, without consideration of costs; the process for verifying the scientific underpinnings of a proposed standard; the boundaries on the Administrator's judgment in accounting for risk and uncertainty in setting NAAQS; EPA's responsiveness to public comments; and the extent to which EPA must respond to requirements exogenous to the CAA that direct EPA to consider impacts of its regulations.