ent levels to 70 ppb
||48 more deaths
|Going from present levels to 65 ppb
||44 more deaths
|Going from present levels to 60 ppb
||35 more deaths
This table, which was made using EPA’s own modeling, indicates that reducing ozone in the Houston area will actually result in increased premature deaths. Whether this predicted result is factual, or if it just highlights flaws in the EPA’s interpretation of the data, it casts doubt on the science being used to justify EPA’s proposed lower ozone standards.
Data collected from Texas hospitals indicates that admissions for asthma are actually highest in the winter, when ozone concentrations are normally lowest. This casts further doubt on the EPA’s assertion that ozone is an important driver of asthma symptoms.
The EPA’s proposed lower ozone standard derives much of its claimed benefits from associating ozone with worsening asthma. The problem with this association is that asthma diagnoses are increasing in the U.S., yet nationwide, air quality is improving. If asthma were actually tied to ozone, you would expect to see the instances of asthma decreasing, not increasing. In fact, data from Texas hospitals show that asthma admissions are actually highest in the winter, when ozone levels are the lowest.
The evaluation of the proposed ozone standard was performed by the TCEQ Toxicology Division, which consists of 10 Ph.D. and five master’s level scientists. Our scientists specialize in toxicology and risk assessment related to air contaminants, and set guidelines and toxicity factors that are adopted by many different states and countries.
The sciences (toxicology, molecular biology, biochemistry, cell biology, chemistry, just to name a few) used to set the EPA’s standards are complex and technical. Toxicology Division members Stephanie Shirley (Ph.D., UT MD Anderson Cancer Center, molecular carcinogenesis), Sabine Lange (Ph.D. UT MD Anderson Cancer Center, biochemistry and molecular carcinogenesis), Neeraja Erraguntla (Ph.D., LSU, physiology, pharmacology and toxicology), and I immersed ourselves in ozone toxicology and epidemiology. We presented a paper titled “A Toxicological Review of the Ozone NAAQS” at various professional meetings, and are helping prepare ground-breaking analyses of the ozone data for publication in peer-reviewed journals.
Below are a few facts and simplified explanations of the TCEQ’s conclusion that a lower ozone standard is not justified.
Also see links to other references and ozone information.
Sensitivity of Asthmatics to Ozone:
- Exposure of human volunteers to ozone showed similar lung effects in asthmatics and in non-asthmatic subjects. Additionally, children are no more sensitive to ozone than are young adults.
Mortality Caused by Long-term Exposure to Ozone:
- Only 1 out of 12 studies considered by the EPA showed an association between long-term exposure to ozone and early death (after considering other pollutants). This single study is used by the EPA as evidence that long-term exposure to ozone causes mortality. Interestingly, this study did not show higher mortality in Southern California, where some of the highest ozone levels in the country are measured.
Many factors influence mortality, and the effect of an increase in ozone by 10 ppb is tiny in comparison to these other influences.
Ambient Ozone Concentrations Don’t Represent Real-world Exposure:
- Ozone is an outdoor air pollutant, because systems such as air conditioning remove it from indoor air. Since most people spend more than 90 percent of their time indoors, we (and the people in the epidemiology studies used to justify lowering the standard) are rarely exposed to significant levels of ozone.
- Even people who work outdoors are exposed to, at most, 60 percent of the ozone concentration that is measured at an ambient monitor. Additionally, there are ozone standards particularly for workers to ensure that they are protected.
- For ozone to cause a slight change in lung function in clinical studies, people need to be exposed to outdoor levels of ozone for hours while vigorously exercisin