From the Document: "Methane, however, when released or allowed to escape into the atmosphere (commonly referred to as 'vented' and 'fugitive' emissions, respectively), can affect human health and safety and the environment. The U.S. Occupational Safety and Health Administration lists methane as both an asphyxiant and an explosive, as increased concentrations in local settings can jeopardize worker safety. Further, the U.S. Environmental Protection Agency (EPA) classifies methane as both a precursor to ground-level ozone formation (commonly referred to as 'smog') and a potent greenhouse gas (GHG), albeit with a shorter atmospheric life than CO2 [carbon dioxide]. Methane's effect on climate change is up to 34 times greater than that of CO2 when averaged over a 100-year time period and even greater when considered over the first 20 years after it is emitted. Arguably, any increase in methane emissions may counteract some of the environmental benefits that the U.S. economy has to gain by switching from coal or oil to natural gas."
CRS In Focus, IF10752
Congressional Research Service: https://crsreports.congress.gov/