Natural gas has very limited range of flammability -- in concentrations in air below 4 percent and above about 14 percent natural gas will not burn. It also has a very high ignition temperature, about 1,200 degrees F. The high ignition temperature and the limited flammability range make accidental ignition or combustion unlikely.
Odor and the Sense of Smell
Natural gas has no scent or color of its own, so government agencies require utility companies to add an odor. Atmos Energy and many other utilities mix in a harmless gas called “mercaptan,” which has the smell of rotten eggs. We follow precise steps to ensure proper levels of mercaptan are in the natural gas we deliver, so a person with a normal sense of smell will notice a leak if one happens.
Some people, however, do not have a normal sense of smell and can only detect the rotten egg odor at very high levels or cannot smell it all. Reasons for this include:
- Colds, sinus conditions, and allergies.
- Limited or no sense of smell, caused by head injury, infection or nose blockage.
- Long-time exposure to mercaptan, which can desensitize one’s sense of smell.
- Use of tobacco, alcohol, and some medications or narcotics.
- Other strong scents nearby that mask the rotten egg odor.
If a medical condition or other factors might prevent you from smelling a natural gas leak be sure to use your other senses too: listen for a hiss or roar; look for clues like blowing dust, bubbling water or dead vegetation near a gas line.
“Flaring” is a standard industry practice in which trained crews oversee a controlled burn of natural gas.