As the manufacturer of natural gas odorizers, we are frequently asked, “What is the chemical added to natural gas to make it smell?”

Odorizing Natural Gas

In “What is Natural Gas Odorization?” we mention that natural gas by itself is odorless and because it is combustible an odorant is injected into the gas at a federally regulated level so that it can be perceived through an individual’s normal sense of smell.

That odorant is mercaptan.

What is Mercaptan?

Mercaptan is a colorless flammable gas with an unpleasant odor often described as rotting cabbage or rotten eggs. Of course we use it as an odorant, it is perfect. When you smell it, you want to leave. That is the intention for a gas odorant, to alert people that a flammable gas is present and to leave.

The gas is also used in the production of jet fuels, pesticides and plastic, along with the synthesis of methionine. Methionine is an amino acid and used as a supplement for poultry and other animal foods.

Mercaptan MSDS

The material safety data sheet (MSDS) lists methanethiol as a “colorless gas with an extremely unpleasant odor.” At very high concentrations it is toxic and affects the central nervous system. Its penetrating odor provides warning at dangerous levels. The gas can be perceived at an odor threshold of 1 ppb, and OSHA has a Permissible Exposure Limit for mercaptan of 10 ppm.