Houston Mayor Bill White on April 23 asked a team of analysts to study the city’s air quality and to provide, within a year, guidelines to aid future air quality decisions.
“We need their advice on the health risks of pollution,” said White, who identified ground-level ozone, soot, and air toxics as requiring special attention.
“We are going to take on this problem, and this is exactly the kind of expertise to help draw up our battle plans,” he said.
According to the U.S. Environmental Protection Agency (EPA), however, the air quality in Texas as a whole and Houston in particular has dramatically improved over the past 30 years, as noted in a 2005 report by the agency.
In Houston, under EPA’s one-hour standard, ozone pollution has declined by an average 78 percent since 1975. Under EPA’s eight-hour standard, ozone has declined by 70 percent on average. And toxic air emissions in Texas have declined by more than 63 percent.
Monitoring Shows Clean Air
The Houston area has the most extensive monitoring network of any city in the United States. Stricter federal and state standards are already in the works, and regulated industries face incentives to improve efficiency and reduce waste and thus remain profitable. As a result, the environmental quality in the Houston greater metropolitan area should continue to improve.
However, one would hardly be aware of the Houston area’s rosy environmental future from reading the series “In Harm’s Way” published in January 2005 in the Houston Chronicle. With the high concentration of chemical manufacturing and refining plants in coastal Texas compared to other regions of the country, it is natural that coastal Texas has higher than average emissions and that there is heightened attention paid to those risks.
In a sense, the employees of those plants and the people who live and work in the surrounding communities are living experiments on the effects of human exposure to synthetic chemicals. Yet the Chronicle could produce no evidence that the ambient air levels of chemicals resulted in higher cancer rates among those living and working near the plants. And if employees, those most regularly exposed to the chemicals in question, had higher than average cancer rates, the Chronicle failed to note that as well.
Risks Mostly Hypothetical
Perhaps that is because the current Effects Screening Levels (ESL) do, in fact, provide an adequate margin of safety. They are, after all, set at levels where chemicals should not cause adverse health effects. Even when a particular ESL is exceeded, however, it simply means further study is warranted.
The hypothetical risks posed by Houston’s higher-than-average benzene and formaldehyde emissions should be put in context. While they are potential carcinogens, so are half of all the chemicals that have been tested for carcinogenic effects, both artificial and natural. Natural chemicals in coffee, beer, tomatoes, and common tap water, among the myriad products that have been tested, cause cancer in laboratory rats.
Scientists know it is the dose that makes the poison. The supposed carcinogenic effects of most chemicals are largely an artifact of the testing regime, wherein the maximum dose of a selected chemical that a lab animal can ingest without causing its immediate death is given to a test group of animals, and then the cancer rates of the test group are compared to a control group not given the chemical. Scientists then extrapolate those results to predict cancer rates in humans within a margin of safety.
But there are several problems with this methodology. It is extremely questionable whether the effects of short-term megadoses of a chemical on lab rats provide a good model for predicting the effects of long-term exposure to minuscule doses of the same chemicals on humans. For that matter, the idea that anyone living in an affected community stays within the borders of that community, day after day, for 70 years never leaving, continuously being exposed to unsafe levels of the chemicals, is farfetched at best.
Money Better Spent Elsewhere
When setting clean air standards, the most important questions to ask are: Would the benefits of stricter standards in terms of human health and welfare outweigh the health and economic costs incurred by the proposed standards? And, are the costs likely to deliver more health and welfare benefits than other allocations of scarce public resources?
Researchers at the Harvard Center for Risk Analysis found that controlling benzene emissions at chemical manufacturing plants would cost approximately $526.3 million to save one hypothetical year of one life. How many women could we screen and treat for cervical or breast cancer with those dollars? How many doctors could be trained, police put on the street, or child welfare case workers hired for the same dollars?
Whether the air quality standards for Houston and surrounding communities should be made stricter should be determined by EPA in consultation with the Texas Commission on Environmental Quality and the affected communities.
Such decisions should not be made on the basis of overblown fears concerning an undocumented link between current air quality and cancer rates. Rather, they should be informed by the best available science, taking into account the limits of the tests used to set risk standards. In addition, there should be an accurate accounting of any harms realistically expected to be prevented by strengthening air standards, weighed against any harms that would likely result from the standards being considered.
H. Sterling Burnett ([email protected]) is a senior fellow at the National Center for Policy Analysis, a nonpartisan, nonprofit research institute based in Dallas.
“In Houston, under EPA’s one-hour standard, ozone pollution has declined by an average 78 percent since 1975. Under EPA’s eight-hour standard, ozone has declined by 70 percent on average.”