ScienceDaily: A team led by environmental engineers from Drexel University are the first independent researchers to take a closer look at the air quality effects of natural gas extraction in the Marcellus Shale region of Pennsylvania. The group used a mobile air quality monitoring vehicle to survey regional air quality and pollutant emissions at 13 sites including wells, drilling rigs, compressor stations and processing areas. Their work establishes baseline measurements for this relatively new area of extraction....