Since the beginning of 2008, natural gas exploration activities in the Marcellus Shale Formation have increased significantly in the Commonwealth of Pennsylvania—more than 2,349 wells have been drilled, primarily in the southwest, northeast and northcentral regions. In response to the increased number of well sites and concerns about the impact of the Marcellus Shale natural gas development activities on air quality, the Pennsylvania Department of Environmental Protection (PA DEP or Department) launched a short-term, screening-level air quality sampling initiative in the northcentral region in August 2010, culminating in December 2010. This report includes the findings of the screening air sampling surveys conducted by PA DEP in Bradford, [...]