Smelling gas is frightening, but knowing exactly what to do — and what not to do — can prevent a dangerous situation from becoming a catastrophic one. Gas leaks kill people every year in the UK, usually because of sparks from electrical switches igniting accumulated gas. This guide tells you precisely what steps to take if you smell gas in your home.
- Do not turn any electrical switches on or off — this includes lights, fans, and appliances
- Do not smoke, use a lighter, or strike a match
- Do not use your mobile phone inside the building
- Turn off your gas supply at the meter (the handle should be perpendicular to the pipe)
- Open all windows and doors to ventilate
- Leave the building and do not go back in
- Call National Gas Emergencies: 0800 111 999 (free, 24/7) from outside
- Call us on 01315631581 — our Gas Safe engineers attend within 30 minutes
What Does a Gas Leak Smell Like?
Natural gas is odourless in its raw state, but gas suppliers add a chemical called mercaptan (ethanethiol) specifically so that leaks can be detected by smell. The smell is typically described as rotten eggs, sulphur, or a strong chemical odour. Even a faint whiff of this smell indoors should be taken seriously — do not dismiss it or wait to see if it gets stronger.
Some people are less sensitive to the smell of mercaptan, particularly elderly individuals. If someone in your household has a reduced sense of smell, a carbon monoxide and gas alarm is strongly recommended.
Why Are Electrical Switches So Dangerous?
Gas is lighter than air and disperses quickly in ventilated spaces, but in an enclosed room it can build to explosive concentrations very quickly. Natural gas ignites at concentrations between 5% and 15% in air — well below what your nose can detect reliably.
Any electrical switch — including a light switch, fan switch, or pressing a doorbell — creates a tiny spark as it opens or closes. In a gas-rich atmosphere, this spark is enough to ignite the gas instantly. This is why the instruction to not touch any switches is absolute, not advisory.
What If I'm Not Sure It's Gas?
If you are in any doubt, treat it as a gas leak. The consequences of ignoring a real gas leak are far worse than the inconvenience of acting on a false alarm. Other smells sometimes confused with gas include:
- Strong cleaning chemicals or solvents
- A recently extinguished match or lighter
- Decomposing organic matter near drains
- Certain types of paint or adhesive
If the smell is definitely not any of the above, act as if it is a gas leak.
What Causes a Gas Leak?
Common causes of domestic gas leaks include:
- Corroded or damaged gas pipework — particularly in older properties with steel pipework
- Failed joints or fittings — compression fittings that have worked loose over time
- Appliance connection failure — flexible hoses on gas cookers degrade and split
- Damaged boiler components — internal gas valve or heat exchanger failure
- Accidental damage — DIY work or building work striking a concealed gas pipe
Can I Go Back Into My Home After Reporting It?
Not until a Gas Safe engineer has confirmed it is safe to do so. The National Gas emergency service will send a technician to isolate the supply and confirm the property is safe. Our engineers then carry out a full gas tightness test — checking that the entire installation holds pressure with no losses — before restoring the supply and issuing a safety certificate.
Gas Leak Detection in Midlothian
Our Gas Safe certified engineers respond to gas leak emergencies across Midlothian within 30 minutes. We carry electronic gas detection equipment that identifies concentrations far below what the human nose can detect, locate the source precisely, carry out the repair and perform a full gas tightness test before leaving. Call 01315631581 — we answer in 3 rings, day or night.