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 up 0.13 percent of natural gas consumption in 2014. The natural gas industry in the United States goes back to 1821, when natural gas was discovered and used in Fredonia, New York. From the start, the market for natural gas was limited by pipeline technology. The gas for Fredonia, New York in 1821 was supplied through wooden pipes, which were incapable of carrying gas for long distances. In the 1800s, residences in most cities were supplied with town gas generated from coal at local "gashouses." The gas was carried in cast iron pipes, introduced in 1843, typically with bell-and-spigot joints