Make no mistake: High rates of pollution can impair lung function. There is some indication that air pollution in Los Angeles in the 1970s and 1980s did just that. But the United States is now well below those highs, and most of the United States has always been below those old Southern California levels. Even massive reductions in air pollution from current levels would probably have little effect. Schwartz points to an environmentalist-sponsored study that concluded that a reduction in power-plant emissions of 75 percent would reduce hospital admissions for serious respiratory or cardiovascular conditions by a mere 0.2 percent to 0.6 percent.
It's a mystery why asthma rates have soared. Maybe kids spend more time indoors in houses that, since the energy crisis of the 1970s, are efficiently sealed off from outside air, and so trap irritants like dust mites, cockroach droppings and pet dander. Maybe increasing obesity and declining physical activity play roles. Some researchers have even pointed to the declining use of aspirin or the generally cleaner, less infectious world kids live in today, which might mean that their immune systems overreact to things like dust.
Given all of this, Kerry's implied pledge to end the asthma epidemic stands as one of the emptiest political promises of all time. Is he going to launch a crusade against pet dander if that's proven a major cause of the epidemic? But for Bush critics, all medical uncertainties and research imponderables disappear before their one all-purpose epidemiological insight: It is George Bush's fault.