Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock () or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Methane is an odorless, colorless, flammable gas. It is used primarily as fuel to make heat and light. It is also used to manufacture organic chemicals. Methane can be formed by the decay of natural materials and is common in landfills, marshes, septic systems and sewers.

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.

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.

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 or food preparation or when children eat contaminated soil.

Methane gas does not pass readily through intact skin. Methane in its extremely cold liquefied form can cause burns to the skin and eyes.

Since it's a "simple asphyxiant," methane can displace available oxygen. There are no workplace limits for methane allowed in the air. No standards exist for the amount of methane allowed in the air of homes. The limiting factor is the amount of oxygen available. The minimum oxygen content in the home or workplace should be 18%.

The Wisconsin Department of Natural Resources regulates the amount of methane that can be released by industries.

There is currently no state or federal drinking water standard for methane.

Everyone's Reaction is Different

A person's reaction to chemicals depends on several things, including individual health, heredity, previous exposure to chemicals including medicines, and personal habits such as smoking or drinking. It’s 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.

Immediately or shortly after exposure to oxygen levels of less than 15% in air, a person may feel tired, dizzy, and have a headache.







Methane is rapidly eliminated from the body. Although methane can be measured in exhaled breath, urine, blood, and other tissues, no reliable method exists to determine the level of exposure. There are currently no tests available to evaluate the health effects of methane exposure.

Seek medical advice if you have any symptoms that you think may be related to chemical exposure.

Questions? Can't find what you're looking for? Email:

Last revised June 15, 2022