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
Trace gas the major greenhouse gases are water, carbon dioxide, methane, nitrous oxide, ozone, and CFCs. These gases can absorb infrared radiation from the Earth's surface as it passes through the atmosphere. The most important greenhouse gas is water vapor because it can trap about 80 percent of outgoing IR radiation. The second most important greenhouse gas, and the most important one affected by man-made sources into the atmosphere, is carbon dioxide. The reason for why greenhouse gases can absorb infrared radiation is their molecular structure. For example, carbon dioxide has two basic modes of vibration that create a strong dipole-moment, which