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
Atmosphere may have outer atmospheres with compound molecules. Atmospheric pressure at a particular location is the force per unit area perpendicular to a surface determined by the weight of the vertical column of atmosphere above that location. On Earth, units of air pressure are based on the internationally recognized standard atmosphere (atm), which is defined as 101.325 kPa (760 Torr or 14.696 psi). It is measured with a barometer. Atmospheric pressure decreases with increasing altitude due to the diminishing mass of gas above. The height at which the pressure from an atmosphere declines by a factor of "e" (an irrational number