Methane is a chemical compound composed of one atom of carbon and four atoms of hydrogen (CH4). It is a simple alkaline and one of the major components of all natural gasses. Methane gas itself is not toxic, but if it is allowed to fill an enclosed room it can displace the oxygen and act as an asphyxiant. Also, if methane is burned in an area with no ventilation, it can produce carbon monoxide, according to MethaneGasDetectors.com. Both of these results can be fatal.

As methane builds in a room, it begins to take the place of oxygen. According to the Canadian Centre for Occupational Health and Safety, oxygen levels may decrease to a point where they represent less than 18 percent of the air in the room. When this happens, an occupant of the room may begin to feel slightly dizzy and experience a headache. At first, your heart rate may quicken and you may begin to have some loss of coordination. As levels of methane rise and oxygen levels are depleted, you may begin to feel fatigued, and have emotional upsets and trouble breathing. If not removed from the room, you may begin to get nauseous and be unable to move. Oxygen concentrations of 6 percent or lower can cause death. These effects may occur faster if you are exerting yourself in any way while the methane is filling the room.

If the methane produces carbon monoxide, you may begin to experience the symptoms associated with that type of poisoning. The first symptom you may feel is a dull pain in your head, almost like a sinus headache. As you breathe in more of the fumes, the headache may be followed by weakness and dizziness. This may lead to nausea and vomiting and a pain in your chest. If you continue to be exposed to carbon monoxide, your judgment may become impaired and you may get confused and irritable. Finally, you may experience a loss of consciousness, followed by death.

Other effects of exposure to methane gas can include damage to organ tissue from lack of oxygen. Also, in some people this type of gas can be a cardiac sensitizer. A cardiac sensitizer can ultimately cause an irregular heartbeat or sudden death, depending on the person. If you are exposed to too much carbon monoxide from methane, you may end up with permanent brain damage or the onset of cardiac complications later in life.