According to Joel Schwartz, associate professor of environmental health at the School of Public Health, “Air pollution kills about 70,000 Americans each year. Thats more people than die from breast and prostate cancers combined. Air pollution is a huge public health problem.”
The idea that air pollution is harmful is hardly new. However, critics of the previous research of Schwartz and other air pollution researchers have claimed that those who die from air pollution are the very ill who would have died within a few days in any case. This notion is sometimes referred to as “harvesting.”
Using a statistical analysis that can factor out expected deaths, Schwartz debunks this argument in a study, “Harvesting and Long Term Exposure Effects in the Relations Between Air Pollution and Mortality” in the March 1 issue of the American Journal of Epidemiology.
If it were true that people who died from air pollution would have died soon anyway, reasoned Schwartz, then there should be a correspondence between an increase in death rates during or immediately following a period of air pollution and a decrease in death rates a few days later.
“Unfortunately, it doesn’t work like that,” said Schwartz. His analysis looked at three time periods of differing duration in Boston, comparing data on air pollution, deaths, and weather. What he found was that even after netting out any “rebound” of fewer deaths within a few weeks to a few months, the air pollution effect remained, and if anything, got stronger. This may be because air pollution increases the numbers of people seriously ill with heart and lung disease, and therefore at risk of dying.
“Air pollution exacerbates heart and lung diseases,” said Schwartz. “You dont get pneumonia from air pollution, but the pollution may make your case of pneumonia much worse maybe even deadly.”