What does natural gas smell like?

By About Pipelines editors · November 4, 2026

If you smell gas now: leave the building or area immediately, without switching anything on or off, and call 911 or your gas utility's emergency line once you are outside and well away. Do not go back in until the utility or fire department says it is safe.

Natural gas is one of the most common fuels in Canadian homes, used for furnaces, water heaters and stoves. Because a leak can cause a fire or explosion, utilities make sure you can smell it. Knowing what that smell is, and the other signs of a leak, helps you act quickly.

Natural gas itself has no smell

Natural gas is mainly methane. In its pure form it is colourless and odourless, so a leak would be impossible to notice by smell. To solve that problem, gas utilities add a small amount of an odorant to the gas before it reaches customers. The odorant is a sulphur compound from the mercaptan family, the same group of chemicals responsible for the smell of skunk spray and rotten eggs.

FortisBC, British Columbia's largest gas utility, says it adds the odorant mercaptan to natural gas so you can smell it in the rare event of a leak. Propane is odourized in the same way.

What the odorant smells like

Most people describe it as:

• rotten eggs
• sulphur
• a skunk-like smell
• rotting cabbage

The smell is deliberately strong. You should notice it at concentrations far below the level at which gas could ignite.

Why you might not smell a leak

The odorant is a safeguard, not a guarantee. Some situations make a leak harder to notice:

• A reduced sense of smell. Age, colds, allergies, some medications and smoking can all dull the sense of smell, and some people cannot detect the odorant at all.
• Getting used to it. After a while in the same room, the nose can stop registering a smell.
• Odour fade. In rare cases the odorant can be absorbed by soil or new pipe, so gas leaking underground may smell weaker by the time it reaches the surface.
• Masking smells. Cooking, paint and other strong odours can cover it.

That is why it helps to know the other signs too.

Other signs of a gas leak

Along with the smell, FortisBC lists a hissing sound, a damaged connection, and dead or dying vegetation around a gas meter, appliance or line as possible signs of a leak. Outdoors, near a buried pipeline, the restored page What should I do if I see a pipeline leak? lists further signs:

• a whistling, hissing or roaring sound
• damaged or discoloured vegetation over the line
• a build-up of frost on the ground or pools of liquid
• bubbles rising in standing water
• isolated vapour or mist clouds

Note that large transmission pipelines may carry gas that has not yet been odourized. Odorant is normally added when gas enters the local distribution system, so a transmission leak may not smell of rotten eggs at all. Treat the other signs seriously.

What to do if you smell gas indoors

Follow your gas utility's instructions. The steps below reflect the public guidance published by Canadian utilities such as FortisBC and Enbridge Gas:

1. Leave immediately. Get everyone, including pets, outside. Leave the door open behind you, and leave any windows that are already open as they are.
2. Do not create a spark. Do not turn lights or appliances on or off, use a phone, light a match, smoke, start a car in an attached garage, or ring a doorbell.
3. Call from a safe distance. Once outside and well away from the building, call 911 or your gas utility's 24-hour emergency line. The number is on your gas bill and the utility's website.
4. Stay out. Do not go back in until the utility or fire department tells you it is safe.

Do not try to find the leak yourself, and do not try to shut off the gas at the meter unless the utility or emergency services tell you to.

What to do outdoors or near a pipeline

If you notice a gas smell outside, or any of the signs above near a pipeline right-of-way, move away from the area, upwind if you can. The restored safety page on recognizing an emergency advises walking into the wind for at least 750 metres, warning others nearby, avoiding anything that could cause a spark, calling 911, and then calling the pipeline company using the emergency number on the nearest pipeline marker. If you are operating equipment and hit a line, shut it off only if it is safe to do so, and leave it where it is.

Sour gas is different

Some raw natural gas in Western Canada contains hydrogen sulphide (H2S), known as sour gas. H2S also smells of rotten eggs at low concentrations, but at higher concentrations it can deaden the sense of smell, so the absence of a smell is not a sign of safety. Sour gas facilities have their own emergency planning, and residents near them receive specific instructions from the operator and the provincial regulator.

Carbon monoxide is a separate hazard

A gas leak and carbon monoxide (CO) poisoning are different problems. CO is produced when fuel burns incompletely, for example in a poorly maintained furnace or a blocked vent. It has no smell, and the odorant in natural gas will not warn you about it. Every home with fuel-burning appliances needs working CO alarms, and appliances should be serviced regularly by a licensed technician.

Sources

• FortisBC, Gas leaks and odour
• Enbridge Gas, Smell gas? Act fast
• Government of British Columbia, Natural gas safety brochure
• Canadian Centre for Occupational Health and Safety, Hydrogen sulfide