Methane is a colourless gas, odourless at low concentrations, but with a sweetish chloroform-like odour at high concentration. It is highly combustible, and mixtures of about 5 to 15 percent in air are explosive.
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Common name: Methane, CH4, natural gas, methyl hydride, marsh gas, biogas and fire damp.
Use
As the major constituent of natural gas, methane is burned to directly heat homes and other commercial buildings. It is also used as a fuel in power stations to produce electricity. Methane is used widely in the chemicals industry in the production of more complex chemical compounds.
Releases to the environment
Methane occurs naturally in the environment. One of the major sources is from the decomposition of plant and animal matter by methane producing bacteria. On a global scale, the human activities that result in the most methane emission, in descending order of importance are: livestock farming, production of fossil fuels, wet rice cultivation, biomass burning, landfill and domestic sewage.
Impacts on the environment and human health
Methane is the second most important greenhouse gas and the main environmental concern is therefore its influence on climate change. At artificially high concentrations methane may affect the brain and ultimately leads to suffocation. Methane gas build-up from landfill sites is a potential explosive hazard.
International actions
The emissions of methane and the other five main greenhouse gases are under the United Nations convention on climate change - the Kyoto Protocol. Furthermore methane is on the EU-Commissions EPER list and listed in the PRTR Protocol under the Århus Convention.
CAS NO: 74-82-8