Why is Pollution from U.S. Manufacturing Declining?

In the 1960s, there were worries that U.S. economic growth would lead to increasingly dangerous levels of pollution, and that by the year 2000, air pollution would make cities like Los Angeles and New York uninhabitable. Instead, U.S. air quality has improved dramatically since then. Between 1990 and 2008, emissions of the most common air pollutants from U.S. manufacturing fell by about two-thirds, even as real output from U.S. manufacturing grew substantially (see Figure 1).

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