The U.S. Environmental Protection Agency (EPA) has this year proposed revisions to ground-level ozone standards. On hot, smoggy summer days on the Wasatch Front, when we have red air-quality alerts that health-sensitive people should avoid outside exertion, levels of ground-level ozone over the national standard are the most common problem. This is referred to as being “out of attainment” with those standards. Many argue that current standards are not high enough to protect our health, that ozone has an impact on health at much lower levels than the current standards would indicate.

As part of the revision process, the EPA invited public comment through hearings and by mail. The public comment period closed last week. Utah Moms for Clean Air submitted the following comment. [Download Utah Moms for Clean Air "Public Comments re: proposed ozone standard."]

Administrator Stephen Johnson
United States EPA
Washington, DC

Re: Docket ID No. EPA-HQ-OAR-2005-0172
Public Comments re: proposed ozone standard

Dear Mr. Johnson:

Utah Moms for Clean Air is pleased to submit these comments on the proposed revisions to the standards governing ozone. Although it has been more than 3 decades since the passage of the Clean Air Act in 1970, the air in many parts of the United States is far from clean. Utah Moms for Clean Air was specifically formed to address the poor air quality that threatens the health of our children and families in Utah. Ozone is one of our primary challenges in terms of poor air quality.

As a group of mothers who are concerned about raising children in an area of poor air quality, we wish to emphasize that it is very important that the EPA heed that aspect of its mandate under the Clean Air Act that requires the new ozone standards be strong enough to protect the public’s health, including the health of “sensitive” populations, such as people with asthma, children, and the elderly. Children and infants are among the most susceptible to the harmful effects of ozone. Eighty percent of alveoli are formed postnatally, and changes in the lung continue through adolescence (1). During the early postneonatal period, the developing lungs are highly susceptible to damage after exposure to environmental toxicants (1-3). Children also have higher minute ventilation, higher levels of physical activity, and spend more time outdoors than do adults (3,4). As a result of all these factors, children have an increased exposure to outdoor air pollution.

The current standards are not adequate to protect public health. This means that we and our children are routinely breathing unhealthy air. We hope that the old standards will not in turn be replaced by standards that also fail to adequately protect public health. Accordingly, we support the adoption of a primary ozone standard of 0.060 ppm/8 hours. We also support the EPA’s proposed secondary standard for vegetation, as it seems to be a more accurate indicator for measuring those impacts.

Ozone is a powerful oxidant and respiratory tract irritant in adults and children, causing shortness of breath, chest pain when inhaling deeply, wheezing, and coughing (5). We routinely see children suffering from these impacts where we live. In addition, children have decreases in lung function, increased respiratory tract symptoms, and asthma exacerbations on days with higher levels of ambient ozone (5-8). Increases in ambient ozone have been associated with respiratory or asthma hospitalizations (9,10), emergency department visits for asthma (12, 13), and school absences for respiratory tract illness (14).

Ozone may be toxic at concentrations lower than 0.08 ppm, the current federal regulatory standard. Field studies suggest potential thresholds of between 0.04 and 0.08 ppm (1-hour average) for effects on lung function (15-17). In a 2003 prospective cohort study published in the Journal of the American Medical Association, Gent and colleagues found an association between ozone and respiratory symptoms in children with asthma at levels below the current EPA standards (18). Mean levels of ozone were 0.059 ppm (1-hour average) and 0.051 ppm (8-hour average). More severe asthmatics, as determined by use of maintenance medications, were particularly vulnerable. In a similarly designed study in infants aged 3 to 18 months, mean ozone concentrations of 0.061 ppm (1-hour average) and 0.055 ppm (8-hour average) were associated with difficulty breathing, particularly in those whose mothers had asthma (19).

Just as concerning as the acute effects of ozone on health is the effect of cumulative exposure throughout childhood. Studies of college freshmen and other young adults suggest that increasing cumulative childhood exposure to ozone may affect lung function when exposed children reach adulthood, particularly in measures of flow in small airways (20-22). Early childhood exposures may, therefore, be particularly important. Children who grow up in areas with poor air quality may suffer permanent impairment in their lung function.

Growing concern is also emerging regarding the relative risks of increased morbidity and mortality among adults. A series of recently published meta-analyses and national-scale epidemiological studies have documented consistent associations between premature mortality and ozone exposures below the current 8-hour standard (23). Controlled human exposure studies of healthy adults have demonstrated reduced lung function, increased respiratory symptoms, changes in airway responsiveness, and increased airway inflammation following 6.6-hour exposures to ozone concentrations of 0.08 ppm (24, 25). More recent studies demonstrate that some of the individuals tested experience these adverse effects at concentrations of 0.06 ppm and below (26).

To protect the nation’s health, it is imperative that the EPA take action to issue a more stringent standard for ozone pollution. Protecting the health of the nation’s population is a clear mandate of the Clean Air Act. Numerous recent studies clearly demonstrate adverse health effects at ozone levels well below the current standard, and even at levels below 0.06 ppm/8 hours, which is the lowest indicator being considered by the EPA in this rulemaking.

Because the law requires that the most vulnerable groups be protected when setting or revising the air quality standards, the potential effects of air pollution on the fetus, infant, and child should be more closely evaluated, and all standards should include a margin of safety for the protection of children. Based on the evidence available, including that presented to the EPA by its own panels of experts, we cannot see how the EPA can possibly comply with its mandate with any standard higher than 0.060 ppm/8 hours as the primary standard.

We understand that during the rule-making process for particulate matter (another major public health concern here in Utah), you cited “scientific uncertainty” as a reason for the EPA not issuing a more protective particulate matter standard. We understand that even with the current compelling scientific data supporting a stricter standard for ozone, there is still room for “scientific uncertainty.” In drafting the Clean Air Act, Congress realized that “perfect” information about exposure–response relationships would never be available in setting National Ambient Air Quality Standards. The Clean Air Act is founded on the precautionary principle, and directs the EPA, in cases of scientific uncertainty, to err in favor of protecting the public health. It would be inexcusable for the EPA to once again use “scientific uncertainty” as a reason for failing to act in favor of the strictest standard.

Based on the strength of the scientific evidence of the adverse health effects of ozone air pollution and the magnitude of the public health impact on the United States’ population, especially on children, Utah Moms for Clean Air strongly recommends the EPA take action now by issuing the stricter ozone standard of 0.060 ppm/8 hours. We join numerous expert scientific panels and medical associations (27, 28) in this recommendation, including the EPA’s own Children’s Health Protection Advisory Committee and the Clean Air Scientific Advisory Committee. Any action less stringent than a 0.060 ppm/8 hours standard will effectively represent a failure of the EPA to fulfill its mandate under the Clean Air Act.

Sincerely,

Michelle Hofmann, MD, MPH
Dana Clark
Co-founders, Utah Moms for Clean Air

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