Published in ‘The House’ Magazine i.e. The House of Commons September 2021 – It’s time for action against the silent killer in our homes –

There are two versions of this article:-

  1. The article as published in the House (of Commons) Magazine (PDF) and
  2. The word version with footnotes.


Good quality outdoor air is vital. But Brits spend around 90% of their time indoors*1. The most important avoidable contaminants of indoor air are the products of combustion, including the silent killer, carbon monoxide (CO).

What is carbon monoxide (CO)?

CO is a deadly gas that can be emitted from faulty cooking and heating appliances powered by any carbon-based fuel that burns. Fuels include wood, gas, coal, petrol and diesel.

CO cannot be sensed using human senses of smell, taste, sight or touch.

Less than 2% of CO in the air can kill or maim in between one and three minutes.*2

CO symptoms mimic those of viruses including Covid-19, so usually GPs don’t even think about CO.

If a survivor’s blood or breath is tested, the CO will usually have disappeared, so testing living people can lead to dangerous false negatives. It’s wiser to test the air the survivor was exposed to and find the source.

Over 3 million citizens are exposed to levels above 50 parts per million of CO in the UK alone.

Extrapolating from respected university research in 2006 and 2011, more than 3 million people are exposed to levels above 50 parts per million (PPM) of CO in their UK homes*3. WHO guidelines for 24 hours are 6 PPM. The known deaths and injuries cost the UK taxpayer £178 million a year *4.

CO causes brain damage including dementia.

Exposure to CO above the WHO guidelines can cause brain damage, including a 1.6 x higher risk of dementia in those exposed to CO*5.

How could CO be proved?

The gas emergency service could relight gas appliances and provide a free sweep test for CO under BS 7967. HSE has recommended testing by the gas emergency service described by Lord Hunt of Kings Heath as a ‘no brainer’, Why won’t HSE take action?

Trials have been undertaken by Northern Gas Networks*6; testing would add under 7 minutes to each visit. Ofgem has the funds to pay for it – to give survivors and their medics confirmed proof.

Why don’t MPs take action?

Because it’s a Catch 22 – to prove CO, you have to prove exposure to CO, which is invisible and cannot be sensed by human senses. Proof and therefore data are virtually impossible. Please watch our 1 minute film on our website about Sue who had carbon monoxide poisoning. Sue’s medics thought she had been taking cocaine!

Survivors say that not being able to prove exposure to CO, even to medics and family, is worse than their life changing injuries. Lack of proof leads to lack of awareness and safety improvements.

121 MPs signed EDM 1032 urging testing in 2007. A safe appliance is energy efficient.

The charity CO-Gas Safety considers that the changes it seeks on behalf of victims/survivors are blindingly obvious and have been for decades. Indoor air contaminated by CO is a worldwide problem.

Surely testing for CO is an easy win for Boris to show leadership at COP26?



*2 (see Para 74 table 23 page 26).





Stephanie Trotter OBE is a barrister and President/Director of the independent, registered charity, CO-Gas Safety. For more information about CO-Gas Safety please visit or contact Stephanie via email at

Also see PDF version here.