Holes in EPA’s Ozone Policy
No sooner has EPA implemented its tough new 8-hour ozone standard, than the agency is considering a substantial new clampdown on federal smog limits. The Clinton administration concluded back in 1996 that trying to attain the 8-hour standard would cause net harm to Americans. Bearing down still further on ozone would guarantee permanent employment for EPA’s air pollution warriors, but at a high price for the American public, who will foot the bill for EPA’s regulatory tunnel vision.
A new EPA Staff Paper on ozone claims that meeting the current 8-hour ozone standard of 0.085 parts per million (ppm) “would likely result in substantial reductions in exposures of concern and associated risks of serious health effects.” But EPA’s staff plans to assess the benefits of going even lower–down to 0.07 or 0.06 ppm, because “there is risk of moderate or greater lung function decrements in children, hospital admissions, and mortality from [ozone] resulting from exposures across the range of levels allowed by the current standard.” The Staff Paper is a follow-up to EPA’s Air Quality Criteria Document (AQCD) for ozone. The AQCD is an in-depth analysis of health effects and related issues that the agency must conclude as a prelude to tightening pollution standards.
Despite its sober tone and measured language, the Staff Paper nevertheless substantially exaggerates the health risks of ozone at contemporary U.S. levels. If anything, what has become clear over the last several years is that ozone is having, at worst, a tiny effect on Americans’ health and welfare. Ironically, it is EPA’s own research staff, along with their counterparts at the California Air Resources Board (CARB), who have provided much of the analysis demonstrating the mildness of ozone’s public health impacts.
For example, based on recent estimates by EPA scientists, going from ozone levels during 2002, which were by far the highest of the last several years, down to national attainment of the federal 8-hour standard–typically about a 10 to 20% reduction for most non-attainment areas–would reduce premature mortality by 0.06%, respiratory hospital admissions by 0.07% and asthma emergency room (ER) visits by 0.04%. The improvement would be a few times greater if benefits continue to accrue when ozone is reduced from levels that already comply with the federal standard.
Scientists at the California Air Resources Board (CARB) drew a similar conclusion. Based on CARB’s estimates, reducing ozone by about 40 to 50% in California–which essentially means eliminating all human-caused ozone–would reduce premature mortality by 0.05%, respiratory hospital admissions by 0.23%, and asthma ER visits by 0.35%. This is despite the fact that millions of Californians live in areas that have ozone levels far higher than any other part of the U.S.
In other words, large ozone reductions will at best result in tiny reductions in short-term health risks. The story is similar on long-term ozone exposure. CARB’s Children’s Health Study (CHS) followed nearly 1,800 children in 12 California communities with air pollution levels running from near background up to the highest levels in the country. After tracking the children from ages 10 to 18, researchers from the University of Southern California, who carried out the study, reported that there was no relationship between ozone and children’s lung development. In a separate CHS analysis that followed more than 3,500 children for up to 5 years, the USC researchers reported that children in high-ozone communities were 30% less likely to develop asthma, when compared with children in low-ozone communities.
But the risks may be even smaller still. The reason is publication bias and a related problem known as data mining. Publication bias refers to the tendency of researchers to seek publication of and for journals to accept mainly those studies that find a statistically significant effect, while not publishing studies that don’t find an effect. Data mining refers to the risk that analyses of noisy, multivariate statistical data can become fishing expeditions that turn up chance correlations, rather than real causal relationships. As a recent review of air pollution epidemiology studies concluded:
Estimation of very weak associations in the presence of measurement error and strong confounding is inherently challenging. In this situation, prudent epidemiologists should recognize that residual bias can dominate their results. Because the possible mechanisms of action and their latencies are uncertain, the biologically correct models are unknown. This model selection problem is exacerbated by the common practice of screening multiple analyses and then selectively reporting only a few important results.
A number of recent studies have assessed the effects of publication bias and data mining on estimates of air pollution and mortality. Taken together, they suggest that ozone is unlikely to be increasing the risk of premature death. Perhaps not surprisingly, EPA has brushed off these concerns.
The case of hormone replacement therapy (HRT) points up the risk of relying on epidemiological studies for drawing conclusions about small health risks. Based on epidemiological studies of HRT, researchers concluded that not being on HRT increases a woman’s risk of heart disease by a factor of 2. An influential meta-analysis of these studies, published in 1991, helped make HRT one of the most prescribed therapies in the United States. But more recently, randomized controlled trials, which eliminate the possibility of confounding by unobserved factors that affect health, showed that HRT doesn’t reduce heart disease risk and might even increase risk.
With HRT, even a 100% increase in risk based on observational epidemiological studies turned out to be spurious once all confounding effects were genuinely eliminated through a randomized, controlled trial. The putative risks that air pollution studies are attempting to tease out are tiny by comparison–at most a few percent increase in risk–making their results even more precarious. A number of epidemiologists have suggested that epidemiological studies are inherently unreliable for assessing the existence of such small risks.
Even with all the caveats on the health research, let’s assume for the sake of argument that ozone is nevertheless really causing thousands of hospital visits and premature deaths each year. Of course we would all choose to prevent death and disease if we could. But attaining just the current 8-hour standard nationwide will cost at least tens of billions of dollars per year, and likely more than $100 billion per year. We’re talking about costs on the order of about $1,000 per year per American household to reduce total respiratory disease and premature death by at most a few tenths of a percent. Surely additional ozone reductions would have to be near the bottom of any rational list of priorities for improving Americans’ health.
Even the EPA under President Clinton concluded that the costs of attaining the 8-hour standard would outweigh the benefits by a factor of 2, and that was based on the implausible assumption that attaining the standard would cost only $10 billion per year. Nevertheless, EPA’s air warriors are now considering a far tougher ozone standard.
As if the costs of reducing ozone weren’t bad enough, it turns out that ground-level ozone actually has health benefits. Ozone up in the stratosphere protects us from solar ultra-violet (UV) light. Ozone at ground level adds a small increment of additional protection. Reducing this ozone shielding marginally increases people’s risk of developing skin cancer and cataracts. EPA’s ozone Criteria Document claims these effects are too uncertain to bother about:
Within the uncertain context of presently available information on UV-B surface fluxes, a risk assessment of UV-B-related health effects would need to factor in human habits (e.g., daily activities, recreation, dress, and skin care) in order to adequately estimate UV-B exposure levels. Little is known about the impact of variability in these human factors on individual exposure to UV radiation. Furthermore, detailed information does not exist regarding the relevant type (e.g., peak or cumulative) and time period (e.g., childhood, lifetime, or current) of exposure, wavelength dependency of biological responses, and interindividual variability in UV resistance. . . In conclusion, the effect of changes in surface-level O3 concentrations on UV-induced health outcomes cannot yet be critically assessed within reasonable uncertainty.
It’s almost laughable that EPA would claim uncertainty as a reason not to address a potential health risk. EPA normally uses uncertainty as the justification for more stringent regulatory limits. And EPA has for decades not only tolerated, but required the use of computer models with huge known errors and uncertainties as the driver for multi-billion-dollar regulatory and transportation infrastructure decisions.
EPA’s uncertainty claim is bogus in any case. Back in 1997 an internal EPA analysis concluded “any decrease in atmospheric ozone (tropospheric or stratospheric) causes . . . an increase in the incidence of non-melanoma skin cancers. . . The methodology for estimating such increases (of both UV levels and skin cancer incidence) is well established.” In fact, the ozone reductions necessary to attain the current 8-hour ozone standard could easily result in a few thousand new cases of skin cancer and tens of thousands of cases of cataracts each year. The much larger ozone reductions necessary to attain the more stringent standards EPA is now considering could double or treble this toll. The harm from lower ozone levels are sufficient to offset much or perhaps even all of the benefits from further ozone reductions, depending on how large those benefits really are. It seems safe to conclude that EPA has ignored the risks of marginal increases in UV exposure not because of a lack of scientific support, but because of the political and bureaucratic inconvenience of acknowledging the issue.
Why would EPA pursue policies that will make Americans worse off? Single-purpose regulatory agencies inevitably suffer from tunnel-vision–the pursuit of an otherwise worthy goal to the point where it does more harm than good. We have many needs and aspirations, but limited resources of money, time, knowledge, and attention. This forces us to make implicit and explicit tradeoffs every day based on our goals, tastes, circumstances, and financial means. But EPA’s air regulators deal only in air-pollution reduction, and they place their mission ahead of other people’s particular needs and desires.
EPA employees’ jobs, budgets, and power also depend on having a serious problem to solve, and it is these same employees who get to decide when their job is finished. Despite already stringent standards and the small effects of current air pollution levels, EPA will pursue the next increment of air-pollution reduction, and the next, regardless of whether the increasingly marginal benefits are worth having or the costs worth bearing. By pursuing small health improvements at great cost, EPA continues to make Americans worse off overall.
Joel Schwartz is a visiting fellow at AEI.
