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
Phase-out of incandescent light bulbs mercury contamination from CFLs have been raised, but CFLs can be shown to result in less mercury in the environment compared to traditional incandescent bulbs due to the significant reductions in power plant emissions. Thus, use of energy-efficient bulbs can actually reduce the amount of mercury released into the environment. Compact fluorescent lamps start poorly when very cold, and most types cannot be dimmed. A few specialist applications are unsuitable for CFLs. Light emitting diode (LED) lamps are used for both general and special-purpose lighting. Compared to fluorescent bulbs, their advantages are that they contain no mercury, they turn on