One environmental drawback of using the franking process to extract natural gas from shale, is air pollution.
Methane is a main component of natural gas and is 25 times more potent in trapping heat in the atmosphere than carbon dioxide. A number of other air contaminants are released through the various drilling procedures, including construction and operation of the well site, transport of the materials and equipment, and disposal of the waste. Some of the pollutants released by drilling include: benzene, toluene, xylene and ethyl benzene (BTEX), particulate matter and dust, ground level ozone, or smog, nitrogen oxides, carbon monoxide, formaldehyde and metals contained in diesel fuel combustion---with exposure to these pollutants known to cause short-term illness, cancer, organ damage, nervous system disorders and birth defects or even death .