Methane
Methane is a chemical compound with the molecular formula CH4. It is an odorless, colorless flammable gas. Methane is also a primary constituent of natural gas and an important energy source. Burning methane in the presence of oxygen produces carbon dioxide and water. Methane is used primarily as fuel to make heat and light. It is also used to manufacture organic chemicals.
Methane is a greenhouse gas that remains in the atmosphere for approximately 9-15 years. Methane is over 20 times more effective in trapping heat in the atmosphere than carbon dioxide (CO2) over a 100-year period and is emitted from a variety of natural and human-influenced sources. Human-influenced sources include landfills, natural gas and petroleum systems, agricultural activities, coal mining, stationary and mobile combustion, wastewater treatment, and certain industrial process.
Methane can form an EXPLOSIVE mixture in air at levels as low as 5 percent. You can smell leaking methane only when commercial gas utility companies add a chemical smell to it or when it mixes naturally with hydrogen sulfide, causing a "rotten egg" smell. If you can smell it, the level may be too high to be safe.
Methane can also be found in coal gas. Pockets of methane exist naturally underground. In homes, methane may be used to fuel a water heater, stove and clothes dryer.
Methane evaporates quickly. Therefore, most of the methane that ends up in lakes, streams, or soil is eventually released into the air. However, methane that is formed underground and moves through soil can remain unchanged for many years.
Exposure to Methane
Breathing: Most exposures occur when people inhale methane. Methane can go into homes through sewer traps or foundation cracks. People can be exposed by inhaling the chemical at work, cooking on a gas stove, or entering confined spaces such as manholes, silos, animal waste pits, septic tanks and sewers.
Drinking/Eating: Because methane evaporates quickly, it is usually not found in food or drinking water. Very low level exposure can occur when contaminated water is used for drinking and/or for food preparation or when children eat contaminated soil.
Touching: Methane gas does not pass readily through intact skin. Methane in its extremely cold liquefied form can, however, cause burns to the skin and eyes.
Health Effects
Immediately or shortly after exposure to oxygen levels of less than 15 percent in air, a person may feel tired, dizzy, and have a headache.
The following health effects can occur after several years of exposure to methane:
Cancer: Methane is not suspected of causing cancer.
Reproductive Effects: The reproductive and developmental effects of methane are not known.
Organ Systems: No long term health effects are currently associated with exposure to methane.
In general, chemicals affect the same organ systems in all people who are exposed. However, the seriousness of the effects may vary from person to person.
A person's reaction depends on several things, including individual health, heredity, previous exposure to chemicals including medicines, and personal habits such as smoking or drinking.
It is also important to consider the length of exposure to the chemical; the amount of chemical exposure; and whether the chemical was inhaled, touched, or eaten.
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