Environmental policies matter for growing megacities

Purdue University News: A new study shows clean-air regulations have dramatically reduced acid rain in the United States, Europe, Japan and South Korea over the past 30 years, but the opposite is true in fast-growing East Asian megacities, possibly due to lax antipollution rules or lack of enforcement.

The U.S. Clean Air Act began requiring regulatory controls for vehicle emissions in the 1970s, and 1990 amendments addressed issues including acid rain. Similar steps in the European Union, Japan and South Korea over the past three decades have reduced nitrate and sulfate in rain - components contributing to acid rain, said Suresh Rao, Lee A. Reith Distinguished Professor of Civil Engineering and Agronomy at Purdue University.

The effects of acid rain can propagate through aquatic ecosystems such as lakes, rivers and wetlands and terrestrial ecosystems including forests and soils, negatively impacting ecological health.  Researchers have now used publicly accessible data, collected weekly or monthly at numerous monitoring sites during the period from 1980-2010, to track "wet deposition" of nitrate and sulfate near several U.S. and East Asian cities. The pollutants, products of fossil fuel combustion, are emitted by cars, trucks and buses. Pollutants rise up into the atmosphere and accumulate until being washed down as wet deposition by rain or snow or as "dry deposition" between rain events.

Fast-growing cities in East Asia that lack regulations or enforcement show a dramatic rise in acid rain, according to the new study completed by Purdue researchers. "Our analysis of wet deposition (acid rain) data provides compelling evidence that clean-air policies and enforcement of environmental regulations are profoundly important," Rao said.

...Severe problems with air pollution also are evident in particulate matter (PM) concentrations contributing to smog. In a recent study published in the Lancet journal, PM pollution was the fourth-leading risk factor for death in China and may be linked to 1.2 million premature deaths in 2010. Similar problems exist in cities in India, where air pollution is estimated to contribute to about 600,000 premature deaths, according to the Lancet study...

Seoul and the Han River, shot by :Patriotmissile, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license