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
Suicide in the United Kingdom (4 per cent). Hanging is the most common method used by women, closely followed by self poisoning. Inhalation of domestic gas was the most common method of suicide during the mid-twentieth century. It was completely eliminated by the 1990s as a result of the replacement of coal gas containing toxic carbon monoxide by the non-poisonous natural gas. Later, suicide by inhalation of carbon monoxide from car exhausts became common, but has declined since the introduction of catalytic converters. Age-standardised rates generally fell between 1981 and 2007, with rates in subsequent years increasing to reach a peak of 11.1 deaths per