No one wants to live near a toxic waste dump. The trouble with environmental pollution is that the source is usually diffuse. Even if you can look out your window and see a beautiful bucolic setting, you may be exposed to acid rain, water pollution, air pollution. This is one reason it’s so difficult to draw a causal link between pollution and its impacts: there’s typically not a single, specific group of people who have been exposed. Instead there are levels of exposure, and because of geographical as well as chance factors the levels may not be easily predictable.

Another reason is that the impacts may be hard to detect. It was difficult enough for scientists to link cigarette smoking to lung cancer. What about looking for mental damage? We’ve known about the effects of lead and mercury for some time. More recent research (described in the August issue of American Psychologist) has focused on the impacts of airborne particles. Mounting evidence suggests that exposure to airborne particulates is associated with cognitive decline in adults, with lower IQ among schoolchildren, and even with attention problems among children exposed in utero.

As the scientists studying smoking and lung cancer knew, it’s hard to prove causality. But controlled studies with mice (by Randy Nelson at Ohio State) have found that mice exposed to levels of air pollution that were equivalent to what a human in a smoggy city might receive took longer to learn a maze, and made more mistakes, compared to a control group. Even more difficult to notice, there’s evidence that air pollution can contribute to anxiety and depression – among humans as well as among Nelson’s mice. There seem to be measurable changes in brain structure associated with exposure to the pollutants.

A third level of abstraction is found in the cause of the behavior. We tend to find it easier to wrap our minds around a problem when there’s a clear villain. Thus the tendency to blame Exxon for the oil spilled when the Valdez ran aground, or to blame BP for the explosion of the Deepwater Horizon. But there’s not a single enemy causing air pollution. In fact, as Pogo said, “We have met the enemy and he is us.” All of us are implicated in demanding and using the products that are causing pollution.

So a broad range of sources is emitting a general set of toxins with a diffuse set of impacts. How do we address that kind of problem? We need to recognize the complexity of the issue, and the psychological factors that are involved both as causes and as effects.

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