Aug. 9 (UPI) -- New research suggests federal environmental regulations enacted under the Clean Air Act are responsible for significant reductions in air pollution emissions over the last several decades.
Between 1990 and 2008, the United States' manufacturing output grew, but industrial air pollution decreased by 60 percent.
The new study, forthcoming in the American Economic Review, showed manufacturers adopted cleaner production processes at least partially in response to environmental regulations.
Researchers at the University of California, Berkeley, looked at manufacturing data related to 1,400 different products made in the United States between 1990 and 2008. The research team also looked at the levels of pollution caused by U.S. manufacturing during the same time period.
By comparing the datasets, researchers were able to determine whether changes in the types of goods being manufactured, production output or technological changes were responsible for shifts in emission levels.
The study results undermined traditional explanations for pollution reductions.
"People often assume that manufacturing production pollutes less today because manufacturing output has declined, when in fact output was 30 percent greater in 2008 than in 1990," Reed Walker, an associate professor of economics, said in a news release. "Others argue that manufacturing has shifted towards cleaner, high-tech products or that the manufacturing of 'dirty' products like steel has moved to China, Mexico or other foreign countries."
Instead, the data showed Our analysis showed U.S. factories are still producing the same spread of goods -- and lots of them.
"But they've taken significant steps to clean up their production processes," Walker said.
Technology improvements have significantly reduced the amounts of nitrogen oxides, sulfur dioxide and carbon monoxide released by industrial production processes, researchers found.
Researchers also found more stringent environmental regulations under the Clean Air Act -- not changes in trade costs or productivity -- best explained the adoption of cleaner production technologies.
"Air pollution levels have plummeted, and the evidence shows that environmental regulation and the associated cleanup of production processes have played important roles in those steep declines," Walker said.
The research offers evidence that environmental regulations can facilitate positive change, but as Environmental Protection Agency acknowledges, "particle pollution and ground-level ozone pollution ... levels are unhealthy in numerous areas of the country."
Particle pollution, including smog and soot, is linked with a variety of health problems -- some deadly -- including cancer and heart disease.
Research has also shown that reductions in air pollution have slowed in recent years.