It is no coincidence that some of the dirtiest industrial operations are falling victim to the global recession. Over the past two decades, much of the world’s manufacturing moved to where pollution standards are little more than mild suggestions. Since small, corner-cutting, inefficient facilities tend to both flout pollution laws and be most vulnerable to a sudden drop in demand, the global recession has hit such operations especially hard. Thousands of factories in China’s Pearl River Delta have shut their doors since late last year, for instance; output of autos, electronics and other goods from factories in Mexico’s Ciudad Juárez, Monterrey and Toluca has fallen so sharply that the amount of cargo trucked across the U.S. border has dropped 40 percent. In India, enough small steel-rolling mills around Delhi have closed that levels of sulfur dioxide (which forms acid rain) fell 85 percent in October 2008 compared with a year earlier. The recession is bringing a green dividend in the developed world, too. Reduced economic activity is projected to cut Europe’s emissions of carbon dioxide, the chief man-made greenhouse gas, by 100 million tons in 2009, and the United States’ by about the same amount.

Recession is not exactly a long-term environmental strategy, obviously. The challenge is to use the downturn to deemphasize manufacturing in favor of cleaner economic activity, and to reengineer what survives so that when the economy revs up it’s not at the environment’s expense.