Natural gas is an efficient, safe, colourless and odourless gas. Surprisingly, most people describe its smell to be similar to rotten eggs – which is far from odourless! However, this strange smell has saved many lives over the years.

The creation of natural gas

Like oil, natural gas is a product of decomposed organic matter, buried in the earth over the past 550 million years. Over time, thick layers of mud, silt, sand and rock settled over the matter, pushing it deeper and deeper into the earth’s crust. Sealed off in an oxygen-free environment, pressure and heat from the shifting surface filled the cracks and crevices with oil and natural gas.

This raw form of natural gas is called methane. Industries use it for jet fuel, pharmaceuticals and livestock feed additives. People around the world rely on a gas supply for warmth and cooking purposes.

Why does gas smell?

The natural gas we know smells bad for a good reason – in case of a gas leak.

In its native state, natural gas is odourless, colourless and tasteless. Gas manufacturers add a harmless chemical called mercaptan, giving natural gas a distinctive stench of rotting cabbages, eggs or smelly socks. And that’s exactly why it is added to natural gas – to make the smallest natural gas leak easily detectable.

The stench of mercaptan

Mercaptan gas is an organic substance, made of carbon, hydrogen and sulphur, and is found naturally in living organisms, including the human body. It is one of the chemicals responsible for the foul smell of bad breath and flatulence. When mercaptan is added to natural gas, it rises and dissipates much like the gas itself, making the two substances ideal companions.

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So, if you ever do smell a natural gas leak, leave the premises immediately, and thank the unmistakable stench of mercaptan. That rotten egg smell could just save your life.