We reported previously here on a study done by Pennsylvania's Department of Environmental Protection finding no air emissions that would be a cause for concern. WHYY is reporting on another study with similar results: "The survey observed four Susquehanna County sites from August to October. DEP official Mark Carmon said the study found elevated levels of methane, propane, butane and other gasses in the air, but nothing surpassing the warning levels for 'air-related health issues.'"
For more, including a copy of that study, see here.
Or for another related article, see here.