Nature World: Samples from the Greenland ice sheet suggest the US Clean Air Act had a clear effect on conditions in the Earth's atmosphere. The discovery by University of Washington atmospheric scientists also alludes to a link between air acidity and nitrogen preservation in snow layers, according to a release by the school.
While the research team had been interested in studying smog, it discovered a link in the geologic record between smog and acid rain. The US Clean Air Act of 1970 was a reaction to air...