The researchers were also able to see a rise in temperatures after 1970 - the consequence of clean air legislation cutting emissions of soot and sulphates.

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While the Kochs have long attracted the ire of liberal activists for underwriting the Tea Party and trying to kill clean air legislation, this was the first time one of their summits was greeted by a protest rally.

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America's clean-air legislation is a help, but Ballard has also wisely sought to recruit industrial partners which have a stake in the old technology.

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Now, with the clean air brought by anti-pollution legislation, British peppered moths are once again peppered.

ECONOMIST: Pollution and evolution

Cheap gas and environmental legislation under the Clean Air Act, aimed at emissions of sulphur dioxide, nitrous oxide and mercury (but not carbon dioxide) from dirty coal plants, accelerated a trend that is set to continue.

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The senator, of course, had a distinguished military record, served as secretary of the navy under Nixon and helped to draft some important pieces of legislation, including the Clean Air Act of 1990 (he was a strong environmentalist).

ECONOMIST: Endangered species

Back in the 1970s and early 1980s, he remembers, environmental legislation floundered: the 1970 Clean Air Act, for example, was meant to result in emissions standards being set for 200 toxic chemicals, but after more than a decade only six had been regulated in this way.

ECONOMIST: www.democracy.com

The legislation, which is an amendment to the Clean Air Act, will codify EPA authority.

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