Since the 1970s, US manufacturing output has risen by 70% but air pollution has fallen by 58%. Was this due to improved abatement technology or shifting dirty production abroad?
Increased net imports of polluting goods account for about 70 percent of the composition-related decline in US manufacturing pollution. The composition effect in turn explains about 40 percent of the overall decline in pollution from US manufacturing. Putting these two findings together, international trade can explain at most 28 percent of the clean-up of US manufacturing.