Gas Leaks: What to Do If You Smell Gas at Home

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Last updated: October 31, 2023

These days, modern gas appliances are designed to be as safe and reliable as they possibly can. Of course, that doesn’t mean that they are completely foolproof in every case. In this article, we are going to discuss what you should do if you suspect that you may have a gas leak in your home.

What Causes Gas Leaks in the Home?

There are principally two gasses which, if they escape into the house, can pose a danger to the property and those living in it. These are domestic, or ‘natural’ gas and carbon monoxide. Each gas is generated from a different source and they pose different types of risks, but they are similar in that they constitute a serious hazard to your health if they are not dealt with straight away.

Each of these gasses leaks into the house for slightly different reasons. In the case of natural gas, the most common reason for a leak is poorly installed or maintained gas appliances, such as the boiler, gas heaters, or the gas cooker.

Carbon monoxide is a normal byproduct of combustion (burning) and is produced whenever natural gas is burned. Because of this, it needs to vented to the outside air. It can build up inside the house due to a faulty or blocked flue or vent.

What Does Gas Smell Like?

Neither carbon monoxide, nor natural gas has a smell that humans can detect. However the domestic gas supply companies add a chemical called mercaptan to the gas as a safety measure, so that leaks are much easier to smell. The smell is variously described as ‘old socks’ or ‘rotten eggs’ and is pretty difficult to ignore.

Because it cannot be detected by smell, domestic carbon monoxide detectors are readily and cheaply available to warn of the gas building up in your home.

Identifying a Natural Gas Leak

The most obvious sign that there is a gas leak in the house is that very distinctive, pungent smell. You are much less likely to hear any hissing as the gas leaks out, although this is possible. Other signs, particularly of a slow leak, include pets being excessively sleepy, or plants near gas appliances wilting.

You may also experience physical symptoms related to gas leaks. For natural gas, these include the following.

  • Headache
  • Dizziness
  • Nausea
  • Unusual tiredness
  • Eye and throat irritation
  • Panting, wheezing or other breathing difficulties

Carbon monoxide has no odour and so it is particularly dangerous, as a considerable quantity may have built up before you become aware of it. The danger comes from the fact that carbon monoxide (CO) binds with red blood cells 200 times more efficiently than oxygen, so the oxygen is displaced and not carried to the tissues and organs that require it. As if that wasn’t bad enough, it forms a chemical called carboxyhaemoglobin, which retains the red colour of the cell, so oxygen levels can fall drastically, without the normal sign of a grey or blue tinge to the extremities which you might expevt to see when the level of oxygen in the blood stream is low . Symptoms of this kind of gas leak are as follows:

  • Headache
  • Tiredness
  • Dizziness
  • Nausea
  • Blurred vision
  • Unconsciousness
  • In the case of extreme exposure, the casualty may appear flushed.

Many of these signs can appear as if the casualty is having a stroke, in fact it has been estimated the in the UK, around 25% of patients admitted to hospital with a suspected stroke are actually suffering from carbon monoxide poisoning due to faulty gas appliances.

Anyone who has gas appliances in their property is advised to install a carbon monoxide detector as a safety device. These cost around £20 and can be an absolute life saver.

What to do if you smell gas at home

Whether you smell a gas leak, or detect it using equipment, such as a carbon monoxide detector, you need to take immediate action to avoid the situation becoming worse. Although the actual hazards posed by the two gasses vary slightly, both types of leak cannot be ignored.

If you suspect a natural gas leak, the major risk is that of fire or explosion. It is essential that you take action immediately to prevent a fire or explosion. The following is a list of things you should and should not do if you smell gas in your home.


  • Extinguish any naked flames such as cigarettes or candles.
  • Open doors and windows in order to ventilate the property.
  • Turn off the gas supply at the meter, unless the meter is in a basement or cellar.
  • Evacuate the house and call the national gas helpline on 0800 111 999 as soon as you away from the house.

Do not

  • Operate any electrical equipment or appliance in the house, including light switches, computers and mobile phones.
  • Return to the building to collect belongings.
  • Enter the cellar or basement if you have one. These areas are more likely to be filled with the escaped gas.
  • Attempt to track down the leak yourself. Wait until a gas safe registered engineer arrives to do this job.

In the event that you have good reason to suspect the presence of carbon monoxide in your home, either because you are experiencing the symptoms listed above, or you carbon monoxide alarm has been activated, here is the recommended advice.


  • Open all windows and doors to allow fresh air into the property.
  • Evacuate the property without delay.
  • If you are sufficiently well, call the national gas helpline number on 0800 111 999.
  • If you feel unwell, call an ambulance using 999.

Do not

  • Re-enter the building until a gas safe registered engineer has declared it safe to do so.
  • Delay in calling for medical help. Carbon monoxide does not pose a fire or explosion risk, so if in doubt, your health is the most pressing concern.

Preventing Gas Leaks in the Home

In the case of gas leaks, the old adage ‘prevention is better than cure’ most certainly holds true. While any appliances will have a finite life, you can extend that life and potentially yours too, by arranging to have your boiler, cooker and any other gas appliances you may have, regularly inspected and serviced. This must, by law, be carried out by a gas safe registered engineer. This relatively inexpensive service, and the purchase of a carbon monoxide alarm, is vital in order to safeguard your home from gas leaks. Also, remember to have the gas emergency number written down so if the unexpected does happen, you are ready to act.

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