White House Sidelines Science in Regulating Ozone

NOTE: The following is one of a series of case studies produced by the Union of Concerned Scientists' Scientific Integrity Program between 2004 and 2010 to document the abuses highlighted in our 2004 report, Scientific Integrity in Policy Making.

In 2008, the White House overruled the unanimous advice of its scientific advisors in order to weaken the Environmental Protection Agency's proposed National Ambient Air Quality Standards (NAAQS) for ozone—an air pollutant associated with respiratory ailments and premature death. 

Scientists at the EPA and the Clean Air Science Advisory Committee (CASAC) worked to review 1700 scientific articles regarding effects of ground-level ozone—a primary component of smog—on the health of humans and ecosystems.  They recommended that EPA strengthen its air quality standards for this pollutant. Despite unanimous support from CASAC for stronger standards, the EPA Administrator and the White House finalized weaker protections inconsistent with the best available science.

Ground-level ozone

Ozone (O3) is a gas found in Earth's upper atmosphere, where it protects us from the sun's damaging ultraviolet radiation. However, when it occurs at ground-level, ozone is dangerous for people and the environment.  Ozone forms from chemical reactions between oxides of nitrogen and volatile organic compounds—both primarily from motor vehicle and industrial emissions—in the presence of sunlight.1

When people breathe air containing ground-level ozone, the pollutant can cause irritation and inflammation of the respiratory system, resulting in serious health effects, including wheezing, coughing, shortness of breath, and even premature death.2,3,4,5 Some plants and ecosystems are also damaged following exposure to ground-level ozone, which disrupts the process of photosynthesis and can damage leaves and reduce crop yields for fruits and vegetables.6

Regulating air pollutants

The Clean Air Act (CAA) mandates that the EPA set and periodically update the National Ambient Air Quality Standards (NAAQS) for six air pollutants, including ozone.7 The CAA mandates that the standard be based upon the "latest scientific knowledge" and include a margin of safety to protect the public health.8   For each of the NAAQS-regulated pollutants, the EPA may set both primary and secondary limits, in order to protect human health and public welfare, respectively.9

Updating the 1997 ozone standards

In 2000, the EPA began the process of reviewing the 1997 NAAQS for ground-level ozone by collecting and analyzing air quality data and scientific assessments of health effects of ozone exposure. After years of work, the EPA Office of Air Quality Planning and Standards (OAQPS) released a 609-page document in 2007, referred to as the 'staff paper,' containing ozone limit recommendations and a review of their work by a congressionally mandated external panel of experts—the Clean Air Science Advisory Committee (CASAC).10  This staff paper represents the scientific assessment that is to be utilized by the EPA Administrator in his limit setting decision making processes—a requirement of the CAA.11

In the OAQPS staff paper, CASAC unanimously recommended tightening the primary ozone standard, from the 1997 limit of 80 parts per billion (ppb), to a level as strict as 60 ppb, and in no case higher than 70 ppb. To support that standard, the committee cited recent controlled clinical studies documenting "statistically-significant decrements in lung function" at concentrations of 80 ppb, and "adverse lung function effects" in some individuals at 60 ppb.12,13,14

Historically, the EPA has set secondary NAAQS that are identical to the primary standards because of uncertainties in the benefits of a tighter secondary standard.  However, following its review of recent scientific evidence, the agency also proposed a more stringent seasonal standard for ozone, to protect crops and other plant life during times of intense exposure. Dr. Rogene Henderson, the chair of CASAC, later testified that "the panel was in unanimous agreement that we now have enough new information to be able to set a cumulative, seasonal secondary standard rather than to default to using the primary standard" and that the EPA staff and the Administrator shared this consensus.15

But Dr. Henderson went on to describe how this scientific consensus was trampled, stating "In this case, policy makers wandered into scientific issues and they did not do it well."16

Political interference ensues

Despite CASAC's consensus on the science, industry groups and local governments actively lobbied both the White House and the EPA to maintain the 80 ppb primary standard.17 

The Clean Air Act forbids the EPA from considering the economic costs when setting NAAQS standards.  However, the White House Office of Information and Regulatory Affairs (OIRA, part of the Office of Management and Budget) does require the EPA to submit a regulatory impact assessment (RIA) whenever it proposes major regulations.  The RIA is an attempt to estimate the economic costs and benefits of a regulation.

In 2007 OIRA manipulated the EPA's RIA for the proposed ozone rule to cast doubt on the health benefits of a lower standard (read more about OIRA's manipulation of EPA science here).18,19  In the case of the NAAQS, the scientific evidence on human health is supposed to trump the economic findings of the RIA, but this interference foreshadowed the battle over the primary and secondary standards.

News reports and Congressional investigations20 revealed evidence that in March 2008 OIRA forced the EPA to weaken its proposed secondary ozone standard.  The evidence suggests that EPA Administrator Stephen Johnson and his staff attempted to push back against these changes but were overruled.  The EPA also released a primary ozone standard that was weaker than CASAC's recommended range.

A March 6, 2008 memorandum from OIRA Administrator Susan Dudley to Administrator Johnson questioned the EPA's scientific basis for the proposed secondary standard, and called on the agency to consider "economic values, personal comfort and well-being."21  The following day, EPA Deputy Administrator Marcus Peacock replied that the EPA was barred by law from considering economic costs of implementing standards, and that the EPA was unaware of "any information indicating beneficial effects of ozone on public welfare."22 OIRA followed up on March 8th with a phone call to EPA, again indicating that they "did not concur" on the secondary standard.23

Confidential talking points prepared for Administrator Johnson's March 11 meeting with President Bush also emphasized the strong scientific support for the EPA's proposal of a more stringent secondary ozone standard.24

The dispute was settled by a last minute intervention by President Bush on the evening of March 11, 2008, the day before the final rule was to be issued.25  The EPA was instructed to make the ozone secondary limit equal to the primary, which triggered an "emergency rewrite" of the final rule.26 The final rule was issued March 12, 2008, with EPA's justifications of the stricter secondary standard deleted from the document.27

That same day Administrator Johnson further overruled CASAC to set the primary NAAQS for ozone at 75 ppb—a level unsupported by the best available science.28,29 Johnson's decision to ignore CASAC's advice mirrored his 2006 decision not to tighten the NAAQS for fine particulate matter, also against the recommendations of his science advisers (read more about the EPA's particulate matter decision here).

The House Oversight and Government Reform Committee—chaired by Rep. Henry Waxman (D-CA)—opened an investigation into the ozone NAAQS process and invited Johnson, Dudley and Henderson to testify.30  In his testimony and in response to repeated questioning, Johnson asserted, despite evidence to the contrary, that the White House did not pressure him and that all of EPA's ozone decisions were his and his alone.31

Rep. Waxman summarized his committee's investigation by stating, "Our investigation has not been able to find any evidence that the President based his decisions on the science, the record, or the law. Indeed, there's virtually no credible record of any kind in support of the decisions."32  An EPA official, voicing the frustrations of many EPA staff members, stated, "I have been working on NAAQS reviews for over 30 years and have yet to see anything like this."33

Update: On January 6, 2010 the EPA issued a proposed rule that would set ozone standards at a level consistent with the advice of CASAC and the EPA's staff scientists. The EPA proposed to set the primary ozone standard to a value in the range of 0.060 to 0.070 ppm and the secondary ozone standard to a value in the range of 7-15 ppm-hours.34


1. EPA website, Ozone – Good Up High, Bad Nearby.
2. Bell, M.L., Dominici, F. and Samet, J.M. 2005. A Meta-Analysis of Time-Series Studies of Ozone and Mortality with Comparison to the National Morbidity, Mortality, and Air Pollution Study. Epidemiology, 16:436-445.
3. Levy, J.I., Chermerynski, S.M. and Sarnat J.A. 2005. Ozone Exposure and Mortality: An Empiric Bayes Metaregression Analysis. Epidemiology, 16:458-468.
4. Ito K., De Leon, S.F. and Lippmann M. 2005. Associations between Ozone and Daily Mortality: Analysis and Meta-Analysis. Epidemiology, 16:446-429.
5. Levy J.I., Carrothers, T.J., Tuomisto, J.T., Hammitt, J.K. and Evans, J.S. 2001. Assessing the Public Health Benefits of Reduced Ozone Concentrations. Environ Health Perspect, 109: 1215-1226; Thurston, G.D. and Ito K. 2001. Epidemiological Studies of Ozone Exposures and Acute Mortality. J Exposure Analysis and Environ Epidemiology, 11:286-294; Anderson, H.R., Atkinson, R.W., Peacock, J.L., Marston, L and Konstantinou K. 2004. Meta-Analysis of Time-Series Studies and Panel Studies of Particulate Matter (PM) and Ozone (O3). Report of a WHO Task Group. Copenhagen: World Health Organization; and Stieb, D.M., Judek, S. and Burnett, R.T. 2002. Meta-analysis of time-series studies of air pollution and mortality: Effects of gases and particles and the influence of cause of death, age and season. J Air & Waste Manage Assoc, 52: 470-84.
6. Environmental Protection Agency. 2007. Review of National Ambient Air Quality Standards for Ozone: Policy Assessment of Scientific and Technical Information ("Ozone Staff Paper"), July, at 7-1 (EPA-452/R-07-003).
7. U.S. Environmental Protection Agency (EPA). EPA's National Ambient Air Quality Standards: The Standard Review/Reevaluation Process.
8. The Clean Air Act.
9. U.S. Environmental Protection Agency (EPA). National Ambient Air Quality Standards (NAAQS).
10. EPA, Ozone Staff Paper, 2007.
11. U.S. Environmental Protection Agency (EPA). EPA's National Ambient Air Quality Standards: The Standard Review/Reevaluation Process.
12. Clean Air Science Advisory Committee (CASAC). 2006. Peer review of the EPA's 2nd draft ozone staff paper. October.
13. EPA, Ozone Staff Paper, 2007.
14. For example, see Adams, W.C. 2006. Comparison of Chamber 6.6-h Exposures to 0.04-0.08 ppm Ozone via Square-Wave and Triangular Profiles on Pulmonary Responses. Inhalation Toxicology 18: 127-136.
15. Henderson, R.F. 2008. Testimony before the House Committee on Oversight and Government Reform at a hearing on the process of the EPA in setting the new ozone national ambient air quality standards, May 20.
16. Henderson Testimony, 2008.
17. Boyle, K. 2008. Industry groups rallying against EPA ozone proposal. Greenwire, February 6.
18. OMB Watch. 2007. Polluted Logic: How EPA's ozone standard illustrates the flaws of cost-benefit analysis in regulatory decision making, December 5, Washington, DC.
19. Patton, V. 2007. Testimony before the Senate Committee on Environment and Public Works, Subcommittee on Clean Air and Nuclear Safety, July 11. Vickie Patton is deputy general counsel for Environmental Defense.
20. Documents from the Committee on Oversight and Government Reform's hearing on the process of the EPA in setting the new ozone national ambient air quality standards.
21. Dudley, S. 2008. Memorandum to EPA Administrator Stephen L. Johnson, Subject: Secondary Ozone NAAQS, March 6.
22. Peacock, M. 2008. Memorandum to Susan Dudley, Subject: Ozone secondary standard, March 7.
23. Peacock, M. 2008b. E-mail from Marcus Peacock to Robert Myers and Charles Ingebreston, March 8, 2:55 p.m.
24. Johnson, S. 2008. Ozone secondary NAAQS, March 11, Talking points (labeled "deliberative and confidential") prepared for EPA administrator Johnson's 11 Mar 08 meeting with President Bush. The document was placed in the public docket after the decision.
25. Dudley, S. 2008b. Letter from Susan Dudley to Stephen Johnson, March 13 (letter was misdated, as was actually transmitted on 12 Mar 08).
26. Weinstock, L. 2008. E-mail from Lewis Weinstock to Richard Wyland, March 11, 9:32 p.m.
27. Draft ozone rule excerpts, page 243, page 252, and page 255.
28. Environmental Protection Agency (EPA). 2008. Press release: EPA strengthens smog standards to better protect human health and the environment, March 12, Washington, DC.
29. Eilperin, J. 2008. EPA Tightens Pollution Standards; but Agency Ignored Advisers' Guidance. Washington Post, March 13.
30. U.S. House Committee on Oversight and Government Reform. 2008. Committee Holds Hearing on EPA's New Ozone Standards. May 20.
31. Johnson, S. 2008. Written Testimony Presented to the Committee on Oversight and Government Reform at a hearing on the process of the EPA in setting the new ozone national ambient air quality standards, May 20.
32. Waxman, H. 2008. Opening Statement, Committee on Oversight and Government Reform Hearing on EPA's New Ozone Standards, May 20.
33. McKee, D. 2008. Email from Dave McKee to Lewis Weinstock. March 11, 9:39 p.m.
34. Environmental Protection Agency. 2010. Proposed Revisions to National Standards for Ground-Level Ozone (web page has been removed).

We Need Your Support
to Make Change Happen

We can ensure that decisions about our health, safety, and environment are based on the best available science—but not without you. Your generous support helps develop science-based solutions for a healthy, safe, and sustainable future.