Hazards of Natural Gas

While natural gas is considered the safest and cleanest fossil fuel for domestic and industrial use, there are inherent dangers to remember.

Natural gas is non-toxic (non-poisonous), but can cause death by suffocation if the gas displaces the air in a confined space. A person will experience the following effects as gas concentration increases:

  • At 25 to 30% gas in air, the oxygen deficiency can cause ringing ears, euphoria, and unexplained behavioral changes.
  • At 50% gas-air mixture, a person taking in a few breaths will be incapacitated and unable to self-rescue.
  • At 75% gas, a person is immediately incapacitated and death will occur in a matter of minutes.

Natural gas flame

Natural gas is always lighter than air, and will rise in a room if allowed to escape from a burner or leaking fitting. On the contrary, propane is heavier than air and will settle in a basement or other low level.

Incomplete combustion can occur when the gas mixture is richer than 10%. When this occurs, there is not enough oxygen to completely oxidize all the carbon to carbon dioxide. Some of the remaining carbon reacts to form the incomplete, less stable compound known as carbon monoxide. Carbon monoxide is toxic (poisonous) and can cause physical illness and death when inhaled under certain conditions. It is lighter than air and mixes very thoroughly.

If not contained, natural gas combustion can be hazardous. Uncontrolled combustion causes a very sharp pressure shock wave through a gas / air mixture. If this type of combustion is in an unconfined space (such as in the open atmosphere), the result is a flash fire. If in a confined space, the result is usually an explosion.

Odorization of natural gas.

Natural gas is odorless, colorless, and tasteless. 


PNG, like most gas utilities, adds mercaptan odorants to all gas. These odorants are commercial blends of sulfur compounds with a distinctive "rotten egg" smell.

The US Department of Transportation requires that most utility gas is odorized, such that a person with a normal sense of smell can detect and identify the gas odor at 1% of gas in air. This is about 1/5th the Lower Flammable Limit.

If you smell any odor or hear any noise (other than a soft whoosh-whoosh) around your meter, get safely away and call PNG immediately at 367-4427.

  • Don't turn on a light.
  • Don't switch on any electrical appliance.
  • Don't light a match.
  • Don't use your phone.
  • Alert others in the house and leave immediately.
  • Call PNG from a neighbor's house or mobile phone outside.
  • Give us your location, and stay there to let us in and give us the facts.

Most gas leaks are harmless. Don't try to fix a leak, work on a gas meter or regulator, or fight a gas fire - get safely away and call PNG immediately.