Inert gas asphyxiation lacks oxygen and consists of an asphyxiant gas (one or more of argon, nitrogen or carbon dioxide), causing the animals to lose consciousness. Argon and nitrogen are important components of a gassing process which seem to cause no pain, and for this reason many consider some types of controlled atmosphere killing more humane than other methods of killing. However, "stunning" is often done using carbon dioxide. If carbon dioxide is used, controlled atmosphere killing is not the same as inert gas asphyxia, because carbon dioxide at high concentrations (above 5%) is not biologically inert, but rather is toxic and also
Natural gas in the United States 25.7 TCF in 2014, an increase of 21 percent. Remaining proved reserves increased overall, from 301 TCF in 2013 to 338 TCF in 2013 (the last year for which reserves are available), an increase of 11 percent. The rise in gas production despite fewer rigs drilling has been explained by the greater efficiency in drilling, and the greater productivity of shale gas wells. Top producing gas fields in the United States, 2013 Most oil fields produce some gas, and vice versa, but the ratio of oil and gas varies considerably. Some gas fields, such as coalbed methane wells, and some