Air pollution isn't good for any of us, but it's especially bad for children and babies. So bad in fact, that economists Michael Greenstone and Kenneth Chay set out to study the correlation between infant mortality and air quality. Their paper, "Air Quality, Infant Mortality, and the Clean Air Act of 1970" compared the reduction of total suspended particulates (TSPs) with changes in infant mortality in parts of the United States. Because the TSP count fell more in some U.S. counties than in others, the researchers were able to use the difference as a variable, and draw a connection between infant health and particulate matter.
They found that 1,300 fewer American infants died in 1972 than if the Clean Air Act had not existed -- a change that worked out to a 0.5 percent decline in infant mortality per 1 percent decline in TSPs.
The Economist wanted to see if the global recession -- and the likely drop in urban air pollution -- has had a similar effect on infant mortality.