The human nose is the most sensitive detector around to measure aroma intensities. Chisholm said the beverage industry primarily uses the distilled oils which tend to have higher aroma intensities. Chisholm intends to continue the studies on lime oils, including examining aroma interactions that may lead to making synthetic lime oil in the laboratory. Clean Air Act reduces acid rain in the Eastern United States By A'ndrea Elyse Messer Public Information Acid rain levels have decreased as much as 20 percent over a large region of the Eastern United States thanks to the Clean Air Act of 1990, according to a Penn State researcher. The pollutants that cause acid rain come from local sources and sources in the Midwest, and affect a wide region up into New England.
Acid rain is caused by sulfur dioxide and nitrogen oxides produced when fuels burn.
It forms when sulfur dioxide and nitrogen oxides in the atmosphere combine with water to form sulfuric acid and nitric acid, respectively. These acids, mixed with rainwater, fall to Earth and can acidify lakes and streams. The source of most sulfur dioxide is high-sulfur coal burned in power plants. Controlling this source of sulfur dioxide production can have a major impact on acid rain. Because nitrogen oxides are generated by a variety of sources including power production, automobiles, the agricultural sector and even lightning strikes and biological processes, controlling or regulating them is much more difficult.