Air Quality Standards:
The Decisionmaking Process II

97-722 ENR

CONTENTS FOR THIS SECTION

"Margin of Safety"

Secondary Standards

Setting NAAQS

Setting and Reviewing NAAQS

Criteria Document
Staff Paper
Clean Air Scientific Advisory Committee

"Margin of Safety"

.....[A]llowing an adequate margin of safety ....[CAA §109(b)(1)]

In setting such [National ambient air quality] standards the [Administrator] should consider and incorporate not only the results of research summarized in air quality criteria documents, but also the need for margins of safety. Margins of safety are essential to any health related environmental standards if a reasonable degree of protection is to be provided against hazards which research has not yet identified. [Senate Committee on Public Works, Report No.91-1196 (1970), pp.9-10]

The phrase, "margin of safety," has been central to several debates.

The phrase seems to imply that NAAQS are based on thresholds that there is a concentration of a pollutant below which adverse health effects do not occur. In this view, the Administrator determines the "no effect" threshold for the pollutant from the scientific evidence in the "criteria document" and then adds a safety factor. From this perspective, the issue is how large the margin of safety should be. In a report on automobile emissions in 1974, a panel of the National Academy of Sciences observed that "the safety factors provided by the air standards are much smaller than is usual in regulating other environmental pollutants such as radioactivity...."5 This could be interpreted as suggesting the need for tighter standards,6 thus providing a larger margin of safety.

The inability of scientists to find clear thresholds has led some to conclude that costs should be considered in setting NAAQS. A National Academy of Sciences panel observed that-

in no case is there evidence that the threshold levels have a clear physiological meaning, in the sense that there are genuine adverse health effects at and above some level of pollution, but no effects at all below that level. On the contrary, evidence indicates that the amount of health damage varies with the upward and downward variations in the concentration of the pollutant, with no sharp lower limit.7

The 1996 reviews of the ozone and PM standards likewise concluded that no threshold of adverse effects could be found for either pollutant. Some argue that if there is no threshold, then there cannot be a margin of safety and as a result the whole NAAQS process of necessity becomes a risk management decision - that is, one in which the Administrator balances risks with costs to decide where to set the standard. Others argue that the lack of a threshold justifies the tightest possible standards.

Another, related debate comes from the view that only in adding a "margin of safety" does the administrator layer a policy judgment onto an objective, scientifically determined NAAQS. Some argue that this judgmental aspect means that the "margin of safety" phrase implicitly endorses the consideration of costs in setting NAAQS; as discussed later, the lead industry sued EPA over lead standards on the basis that the "margin of safety" required EPA to take costs into account in setting NAAQS, but the court ruled that the statute and its legislative history are against that interpretation (Lead Industries Association v. Environmental Protection Agency, 647 F.2d 1 30 (D.C. Cir. 1980)).

The legislative history of the CAA only briefly touches on the "margin of safety" phrase. The Senate Report 90-11% (accompanying legislation that became the Clean Air Amendments of 1970), quoted at the beginning of this section' clearly indicates that the "margin of safety" is designed to protect against the potential for adverse effects to occur at pollutant concentrations below those known to cause harm. Thus, regardless of the existence of a threshold, the margin of safety is a factor the Administrator would consider in making choices involving uncertainties embedded in the definitions of which vulnerable population groups to protect and of what effects are adverse health effects: these issues are discussed later. Similarly, House Report 95-294 (accompanying legislation that became the Clean Air Act Amendments of 1977), after quoting the National Academy of Sciences about the "smaller than usual" safety factor in NAAQS and about the lack of evidence for thresholds, suggested "greater not lesser control of emissions are likely to be needed."' The precautionary premise of the act seems manifest in the phrase "margin of safety" regardless of the existence of thresholds; and the inference that the phrase calls for consideration of costs has been consistently rejected.

Secondary Standards

Any national secondary ambient air quality standard... shall specify a level of air quality the attainment and maintenance of which in the judgment of the Administrator, based on such criteria, is requisite to protect the public welfare from any known or anticipated adverse effects associated with presence of such air pollutant in the ambient air. [CAA § 1 09(b)(2)]

All language referring to effects on welfare includes, but is not limited to, effects on soils, water, crops, vegetation, man-made materials, animals, wildlife, weather, visibility, and climate, damage to and deterioration of property, and hazards to transportation, as well as effects on economic values and on personal comfort and well-being, whether caused by transformation, conversion, or combination with other air pollutants. [CAA §302(h)]

Secondary NAAQS define the concentration of an air pollutant in the ambient air necessary to protect the "public welfare." Secondary standards are implemented in the same manner as primary NAAQS, with the key difference that there is no federally enforceable specified deadline for attainment. Most secondary NAAQS have been set at the same level as the primary NAAQS.

Setting NAAQS

Setting and Reviewing NAAQS

The process for setting a NAAQS is a multistage one, and repeats regularly as the CAA requires each NAAQS to be reviewed every 5 years using the same process, to ensure that each NAAQS is based on the most recent scientific information. 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. Finally, there are a number of regulatory assessment requirements in law that impinge on the process - but have limited substantive impact on the decision itself These stages are discussed below.

Criteria Document

The Administrator shall issue air quality criteria for [each] air pollutant... included... [on the] list.... [CAA §108(a)(2)]

The "criteria document" precedes the NAAQS both in its appearance in air pollution control law and in the process of setting NAAQS. In the early stages of the evolution of Federal air pollution control law, the Federal role focused primarily on research and on providing financial and technical advice to states. This role was exemplified in the requirement that the Public Health Service (which was responsible for Federal air pollution activities before EPA) prepare a "criteria document."

"Air quality criteria [documents] are an expression of the scientific knowledge of the relationship between various concentrations of pollutants in the air and their adverse effects on man, animals, vegetation, materials, visibility, and so on.
"Air quality criteria can and should be used in developing air quality standards. Criteria and standards are not synonymous. Air quality criteria are descriptive; that is, likely describe the effects that can be expected to occur whenever and wherever the ambient air level of a pollutant reaches or exceeds a specific figure for a specific time period."
[Dr. Middleton, Director, National Center for Air Pollution Control, Public Health Service, quoted in Senate Committee on Public Works Report 403 on the Air Quality Act of 1967, p.26.]

Air quality criteria for an air pollutant shall accurately reflect the latest scientific knowledge useful in indicating the kind and extent of all identifiable effects on public health or welfare which may be expected from the presence of such pollutant in the ambient air, in varying quantities. [CAA, § 1 08(a)(2)]

In 1970, when the Clean Air Amendments of 1970 established the federal role in setting NAAQS, the "criteria document" became the basic technical underpinning of the standards-setting process. Explicitly, the preparation, review, and use of the "criteria document" was to be objective and scientifically validated. It is scientifically peer reviewed by an advisory committee - established by statute in the 1977 amendments - and by other federal departments and agencies. Much of the review process is open to the public, and the final criteria document is made public:

The issuance of air quality criteria... shall be announced in the Federal Register and copies shall be made available to the general public. [CAA, §108(d))

The criteria document is prepared in the Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development by EPA scientists (with the advice of and review by a scientific advisory committee, described below). Reviewing the scientific literature for all studies relevant to the air pollutant, the preparers consolidate information pertinent to indicating the kinds and magnitudes of effects resulting from the pollutant's presence in ambient air, assess the robustness of the studies, endeavor to resolve inconsistencies, and evaluate findings. Key components of the scientific evidence include epidemiological studies that examine the relationships between ambient pollutant levels and public health and welfare; clinical studies that examine human responses to controlled levels of pollutants, for example in air chambers; and animal studies. Typically, the studies included have undergone peer review and been published in the open literature, but on occasion some other studies, such as preliminary reports on ongoing research, may be included if they meet other standards of scientific reporting.

Criteria documents are major undertakings: the current ozone criteria document contains over 1,500 pages and evaluates nearly 190 scientific studies; the PM criteria document contains 2,400 pages and evaluates some 80 studies. Each study took about one year to draft; review and revisions took another year to come to closure.

Staff Paper

This [staff paper) assessment is intended to help bridge the gap between the scientific review contained in the [criteria document] and the judgments required of the Administrator in setting ambient standards for PM. Thus, emphasis is placed on identifying those conclusions and uncertainties in the available scientific literature that the staff believes should be considered in selecting particulate pollutant indicators, forms, averaging times, and levels for the primary (health) and secondary (welfare) standards. [EPA, Particulate Matter Staff Paper (1996), p.I-1]

Based on the criteria document, EPA scientists and policy experts prepare a staff paper. It is developed in the Office of Air Quality Planning and Standards of the Office of Air and Radiation. This document is not required by the CAA; it is an administrative step designed to facilitate the EPA Administrator's decision. It lays Out options for a,NAAQS standard e.g., whether to set a standard, at what level(s) it might be set, and methods for measuring compliance - along with justifications from the criteria document. Like the criteria document, the staff paper is reviewed by the scientific advisory committee.

Clean Air Scientific Advisory Committee

The Administrator shall appoint an independent [clean air] scientific review committee [CASAC] composed of seven members including at least one member of the National Academy of Sciences, one physician, and one person representing State air pollution control agencies.

....[T]he [clean air scientific advisory] committee... shall... review the criteria published under section 108 and the national primary and secondary ambient air quality standards promulgated under this section and shall recommend to the Administrator any new national ambient air quality standards and revisions of existing criteria and standards as may be appropriate....

Such committee shall also (i) advise the Administrator of areas in which additional knowledge is required to appraise the adequacy and basis of existing, new, or revised national ambient air quality standards, (ii) describe the research efforts necessary to provide the required information, (iii) advise the Administrator on the relative contribution to air pollution concentrations of natural as well as anthropogenic activity, and (iv) advise the Administrator of any adverse public health, welfare, social, economic, or energy effects which may result from various strategies for attainment and maintenance of such national ambient air quality standards. [CAA, §109(d)(2)]

The 1967 Air Quality Act required the Secretary of HEW to consult with "appropriate advisory committees" (along with Federal departments and agencies) when preparing criteria documents. The Secretary established a National Air Quality Criteria Advisory Committee, having a membership broadly representative of industry, universities, conservation interests, and all levels of government. This committee actively participated in the rewriting of the Sulfur Oxides Criteria Document published in 1969, and in the preparation of subsequent criteria documents. This general requirement for consultation was replaced in 1977 by the specific requirements creating CASAC, with its responsibilities for reviewing the scientific basis of the Administrator's decisions on NAAQS. The legislative history concerning the CASAC provision emphasizes its independence:

This committee is intended to assist the Administrator, but it is also intended to have complete independence. This independence will help provide an outside mechanism for evaluating whether any pollutant may reasonably be anticipated to endanger public health or environment, for evaluating the scientific and medical data which bear on this question, and for reviewing gaps in the available data and recommending additional needs for research. [Committee on Interstate and Foreign Commerce, House Rept. No.95-294 (1977), p.182]

The seven-member CASAC creates a panel to review each NAAQS. This panel consists of the members of CASAC plus consultant members to assure full coverage of the expertises needed to assess fully the issues involved. For the ozone review, a panel of 15 was convened; for the PM review, the panel consisted of 21.

The panel members meet to review each criteria document and staff paper as it is prepared, recommend improvements, and after further meetings and reviews sign off only when they are convinced that each accurately reflects the status of the science. CASAC panel meetings are open to the public.9 These "closure documents" become part of the record for rulemaking. Thus

The independent, scientific review committee's recommendations on these issues will not only aid the Administrator and the Congress, but also the courts in judicial review of any national ambient air quality standard or of the Administrator's failure or refusal to set or revise such a standard with respect to any pollutant. [Committee on Interstate and Foreign Commerce, House Rept. No.95-294 (1977), p 182]

What the closure letter means is that the CASAC panel members agree that the criteria document and the staff paper provide an adequate scientific basis for regulatory decisionmaking. Using formulaic sentences, a closure letter for a criteria document typically reads:

At the September 1995 meeting the Panel came to closure on the Criteria Document. It was the consensus of the Panel members that the Criteria Document provides an adequate review of the available scientific data and relevant studies of ozone and related photochemical oxidants. The document is quite comprehensive and will provide an adequate scientific basis for regulatory decisions on ozone and related photochemical oxidants based on available information. [CASAC Closure on the Air Quality Criteria for Ozone and Related Photochemical Oxidants, letter, from Dr. George T. Wolff, Chair, to Honorable Carol M. Browner, Administrator, EPA (November 28, 1995)]

A closure letter for a staff paper typically says:

It was the consensus of the Panel that although our understanding of the health effects of ozone is far from complete, the document provides an adequate scientific basis for making regulatory decisions regarding a primary ozone standard. [CASAC Closure on the Primary Standard Portion of the Staff Paper for Ozone, letter, from D. George T. Wolff Chair, to Honorable Carol M. Browner, Administrator, EPA November 30, 1995)]

ENDNOTES

5 National Academy of Sciences, Air Quality and Automobile Emission Control, Vol.1 (September 1974), p.6.

6 U.S. Congress, House, Committee on Interstate and Foreign Commerce, Clean Air Act Amendments of 1977, House Rept. No.95-294, to accompany H.R. 6161 (95th Congress, 1st session) (Washington, D.C.: U.S. Govt. Print. Off., 1977), p.182.

7 National Academy of Sciences, Air Quality and Automobile Emission Control, Vol.1 (September 1974), p.17.

8 U.S. Congress, House, Committee on Interstate and Foreign Commerce, Clean Air Act Amendments of 1977, House Rept. No.95-294, to accompany H.R. 6161 (95th Congress, 1st session) Washington, D.C.: U.S. Govt. Print. Off., 1977), p.182.

9 CASAC is subject to the Federal Advisory Committee Act (5 U.S.C. App. 2) which governs public accessibility to committee meetings and products.

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