Climate change in Washington related emissions are the dominant source of GHG emissions and have increased from 61.2 MMT CO-equivalent (CO-e) in 1990 (excluding residual fuel for transportation) to 74.6 MMT CO-e in 2004, while their share has increased from 79% of total emissions to 85% over the past fourteen years. Carbon dioxide is the dominant GHG followed by methane, nitrous oxide, perfluorocarbon and sulfur hexafluoride. Non-energy industrial global greenhouse gas emissions have lowered from 14% to 9%, mainly due to reduced emissions from aluminum production. This has been the result of two key elements: process changes that reduced CO and PFC emissions per
Nitrous oxide and inhibit pain signalling. Exactly how causes the release of endogenous opioid peptides remains uncertain. Nitrous oxide is a colourless, non-toxic gas with a faint, sweet odour. Nitrous oxide supports combustion by releasing the dipolar bonded oxygen radical, thus it can relight a glowing splint. The above reaction is the route adopted by the commercial chemical industry to produce azide salts, which are used as detonators. The gas was first synthesised in 1772 by English natural philosopher and chemist Joseph Priestley, who called it "phlogisticated nitrous air" (see phlogiston) or "inflammable nitrous air". Priestley published his discovery in the book