Study links air pollution to death from heart disease
by Renee Feltz, Contributing Writer
While links between Houston’s air quality problems and respiratory illness are well known, a recent Harvard University study found that long term exposure to air pollution actually poses a greater risk of death from heart disease.
Harvard scientist C. Arden Pope and his colleagues released the latest findings in December from an ongoing study that compares levels of air pollution to the number of people who die from cardiovascular disease. The study looked at 150 cities and more than half a million individuals, using risk factor and mortality data collected by the American Cancer Society and the Environmental Protection Agency. University of Texas school of public health physician George Delclose said that for Houstonians, the most compelling finding from the study was that 45 percent of deaths from heart disease were attributable to air pollution.
"In Houston we have air quality problems and a lot of cardiovascular disease," he said. "We need to pay attention to the results of this study. Even though (heart disease) is most strongly linked to things like cigarette smoking, high blood pressure and cholesterol, that doesn’t mean we should ignore the contribution of air pollution to those deaths."
Though researchers are convinced of the statistical links between air pollution and heart disease, information about the biological mechanisms involved remain largely speculative. The director of environmental health for Baylor College of Medicine's disease prevention and control research, Winifred Hamilton, said there are several hypotheses concerning how pollution may affect heart function. For example, she said fine particulate matter may be breathed into the alveolar sacs deep in the lungs. .Because some particles are too small to be cleaned out through the lung’s natural filtration system, they pass through cell membranes into blood vessels and inflame the innermost membrane of the vessel, causing blockages. Pollutants can also interfere with the nervous system’s ability to regulate heart function.
While the Harvard study provides obvious implications for residents who suffer from the city’s poor air quality, there is no large population-based study that looks at air pollution and heart disease in Houston. Hamilton said the closest thing to such research is a study commissioned by the Houston city council in 1999 that compared levels of fine particulate matter in Houston’s air to two California cities where heart disease studies were conducted. Based on the remote studies, Houston researchers estimated that roughly 400 heart-related deaths could be linked the area’s level of fine particulate matter.
Delclose said more support from regulatory agencies is needed to conduct local studies that compare regional air quality with Houston mortality rates.
"That (information) has important policy implications. I think it would be
of value to people who have the ability to make decisions and write policies here locally," he said. "I'm talking about the mayor's office, I'm talking about the state of Texas, and I'm talking about the different departments of health and different regulatory agencies for air quality."
Other factors, like the proximity of Houston neighborhoods to its sprawling freeways and unique weather conditions, indicate a need for more local, narrowly defined research.
A lack of local information and public dialogue means Houston-area residents are regularly exposed to environmental health hazards they may notunderstand. Media sources generally convey warnings about links between the city's air pollution and lung disease. Because the link to heart disease is more complex, the issue is not often discussed.
The Galveston/Houston Association for Smog Prevention’s executive director, John Wilson, said although researchers have known about the link between heart disease and air pollution within the last decade, it is difficult for groups like GHASP to share that information with the public.
"When I am speaking to most media or even most public audiences they are only interested in a quick sound bite," he said. "People just don’t think of air pollution as impacting the blood, the heart muscle and the heart tissue. . . " Continued on p. 4
It's easier to say what has an easy connection, so that (for reporters) the story is tight and expresses the main point, which is air pollution is bad and you need to avoid it," Wilson said.
Because of the difficulties in conveying the message about the link between dirty air and America’s number one killer, clean air advocates in Houston are hoping that the Harvard study will help draw attention to the problem.
Bonnie New, a Houston area environmental and occupational health physician who co-founded Doctors for Clean Air, said the importance of the connection could not be overstated. "This should come as another one of many wakeup calls to the general public that our air quality crisis is a public health crisis and not some sort of political football," she said.
Renee Feltz is the producer for KPFT News on 90.1 FM.