The Pittsburgh Post-Gazette is running a fascinating in-depth series on air pollution in Western Pennsylvania. While it’s got a local focus, I’m sure people from other regions can identify with some of the problems it highlights, like the difficulties in regulating pollution that easily crosses state lines and the frustration of seeing inadequate Clean Air Act enforcement.
The series also delves into issues of epidemiology. In the introductory article, Region at risk: Can higher rates of death be linked to air pollution?, Don Hopey and Devid Templeton explain that the Post-Gazette analyzed mortality and pollution data to find the following:
The Post-Gazette mapped the mortality rates for heart and lung disease and lung cancer for each of 746 municipalities in the 14-county region and found higher rates around many of the region’s 16 coal-fired power plants and 150 other companies considered by the EPA as major stationary sources of pollution emissions. High mortality rates also turned up irregularly in the “plume shadows” of the utilities and industrial sources, that is the downwind area where their emissions can be transported.
The mortality mapping, while not establishing any direct cause-and-effect link to any single or specific pollution source, shows associations that are consistent with accepted scientific health risk models and formulas used by the EPA and other pollution research scientists. It indicates that pollution may play as big a role in the region’s high mortality rates for those three diseases as Pall Malls, pilsners and pierogies.
It’s great to see journalists using publicly available environmental and health data to investigate this kind of important question, and I’m also delighted to see the Post-Gazette go into detail about the challenges and considerations of conducting this kind of research. Templeton and Hopey spend an entire article explaining how they first approached the research, what kind of feedback they got from epidemiologists, and what kinds of changes they had to make along the way – like adjusting for the population’s age and checking for statistical significance. Here’s their summary of what their findings – and the series of interactive maps that came out of it – can and can’t do:
Acknowledged weaknesses of the Post-Gazette ecological study include the inability to incorporate smoking rates of individual municipalities, along with other lifestyle and socioeconomic factors. Epidemiologists who reviewed our maps and methodologies point to those limitations. But most said the maps serve as an interesting first look at pollution and mortality patterns.
These maps cannot reveal what caused these deaths nor provide a direct link between mortality and sources of pollution. They also cannot say whether pollution was a factor in these deaths that also could be caused or aggravated by smoking, socioeconomic factors, traffic patterns, lifestyle and genetics.
But the maps, along with available scientific research on pollution mortality, do raise issues about potential pollution impacts. Existing scientific models predict similar results based solely on the region’s pollution levels.
I hope that in addition to learning about pollution in Western Pennsylvania, readers of the series will come away with an appreciation of the kind of work involved in answering questions about environmental impacts on health.
The paper has released the first four days of what will evidently be an eight-day series. I’m looking forward to reading the rest of it.