Methane is a colorless, odorless gas that is the primary component of natural gas. It contributes to climate change.
What is methane?
Methane is a colorless, odorless, and extremely flammable gas that can be explosive when mixed with air. It is also called methyl hydride. Methane can be a liquid that needs to be refrigerated. Methane is emitted from several natural and human-related sources. The chemical formula for methane is CH4.
Methane is the primary component of natural gas. Other natural sources of methane include permafrost, termites, oceans, bodies of fresh water, wildfires, mud volcanoes, decaying matter in wetlands, digestive processes of animals, and underground and underwater deposits of methane called methane clathrates.
Human-related sources of methane include emissions from burning fossil fuels, such as coal, gasoline, natural gas, and oil. These emissions can come from vehicles, fuel-burning equipment, operations on oil and gas fields, the processing, storage, and transport of natural gas, and the generation of electricity through coal-fired power plants. Hydraulic fracturing emits methane, which may leak into surrounding water wells, underground mines, and other water sources.
Methane is released from coal deposits during underground and surface mining. Abandoned mines can contain or release methane. Other sources of methane include decomposition of waste in open dumps and landfills.
Methane can be emitted from the digestive processes of domesticated livestock such as cattle, goats, and sheep, and from agricultural feeding operations. It can be produced during the decomposition of agricultural animal waste and released through liquid manure management systems, such as lagoons and holding tanks. It can also be produced when manure is deposited on crop fields or pastures as fertilizer or handled in dry form.
Processes during wastewater treatment can emit methane, as can some of the sludge produced. Another source of methane includes rice cultivation. Methane is used to make ammonia, formaldehyde, hydrogen, and methanol.
Methane is a major greenhouse gas because it absorbs heat in the atmosphere, sending some of the absorbed heat back to the surface of the earth and contributing to climate change. Methane emissions represent approximately 10 percent of all greenhouse gas emission in the United States. Methane is about 21 times more powerful than carbon dioxide in absorbing and keeping heat in the atmosphere. It stays in the atmosphere for approximately 9 to 15 years.How might I be exposed to methane?
Everyone is exposed to low levels of methane by breathing outdoor air. You can be exposed if you live near an oil or gas field, coal mine, abandoned mine, farm, landfill, wastewater treatment plant, or coal-fired power plant.
At work, you can be exposed to methane if you are a farmer or coal miner. You can be exposed if you work at an oil or gas field, hydraulic fracturing operation, landfill, wastewater treatment plant, coal-fired power plant, or facility that uses methane to manufacture other chemicals.How can methane affect my health?
Methane in its gas form is an asphyxiant, which in high concentrations may displace the oxygen supply you need for breathing, especially in confined spaces. Decreased oxygen can cause suffocation and loss of consciousness. It can also cause headache, dizziness, weakness, nausea, vomiting, and loss of coordination. Skin contact with liquid methane can cause frostbite.
If you think your health has been affected by exposure to methane, contact your health care professional.
For poisoning emergencies or questions about possible poisons, please contact your local poison control center at 1-800-222-1222.
This description is based on the information found in the Web links listed with this topic.
Web Links from MedlinePlus (National Library of Medicine)
Emissions of Greenhouse Gases in the U.S.: Methane Emisssions (US Energy Information Administration)
Global Methane Initiative: Frequent Questions (Environmental Protection Agency)
Greenhouse Gases: Frequently Asked Questions (National Oceanic and Atmospheric Administration)
Map of Superfund Hazardous Waste Sites with Methane in the United States. TOXMAP (National Library of Medicine)
Methane Emissions (Environmental Protection Agency)
Methane. Haz-Map (National Library of Medicine)
Methane. Hazardous Substance Fact Sheet (New Jersey Department of Health) (PDF — 698.72 KB)
Methane. Hazardous Substances Data Bank (National Library of Medicine)
Last Updated: March 12, 2013