After a Marcellus gas well is drilled and hydraulically fractured, open flaring is often used to test production of the well. The EPA and Pennsylvania DEP enforce limited air quality regulations around Marcellus Shale natural gas wells and facilities (Most gas sites are permitted individually instead of cumulatively).

A large number of pollutants are released into the air during the flaring process, making it an undesirable practice. Included in these airborne pollutants are the chemicals used to frac the well, as well as any of 5-dozen other pollutants including the following:acetalhyde, acrolein, benzene, ethyl benzene, formaldehyde, hexane, naphthalene, propylene, toluene, and xylenes.

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