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
Sulfur hexafluoride the gas's large molar mass. Unlike helium, which has a molar mass of about 4 grams/mol and gives the voice a childish and a "chipmunk like" quality, has a molar mass of about 146 g/mol, and the speed of sound through the gas is about 134 m/s at room temperature, giving the voice a "demonic" quality when is inhaled. For comparison, the molar mass of air, which is about 80% nitrogen and 20% oxygen, is approximately 30 g/mol which leads to a speed of sound of 343 m/s. Sulfur hexafluoride has an anesthetic potency slightly lower than nitrous oxide. Sulfur