1981: The economic recession of 1981 to 1982 forced the closure of many steel mills and factories in Pittsburgh and throughout Pennsylvania. This produced a sharp reduction in air pollution. Measured in terms of total suspended particulates, or TSPs, pollution fell by a quarter between 1980 and 1982. The improved air quality led in turn to a decline in infant mortality caused by “internal” causes (respiratory and cardiopulmonary deaths, for example). While the number of births in Pennsylvania increased by roughly 3,000, the number of infant deaths actually decreased: from 1,815 in 1980 to 1,595 in 1982. So, each year, 220 infants lived who, if it hadn’t been for the recession, would have died.