Carbon Monoxide smoke alarm
Health & Safety

Carbon Monoxide – The Silent Killer

Carbon monoxide is a colourless, odourless and tasteless gas that is a product of the partial combustion of carbon based fuels such as natural gas, liquefied petroleum gas (LPG), oil and wood. As many of you know carbon monoxide is lethal if inhaled. It interferes with the transport of oxygen by the blood.

Oxygen is transported in the blood by haemoglobin inside red blood cells. Haemoglobin is a protein. Your red blood cells are jam-packed full of haemoglobin and not much else. When red blood cells pass through blood vessel in the lungs they collect oxygen molecules. Oxygen molecules diffuse from the air in the lungs, through the lung wall and into the blood stream and red blood cells. They then loosely bind to haemoglobin molecules at very specific points on those molecules called active sites. Once these active sites are full the haemoglobin molecules cannot carry any more oxygen. Each haemoglobin molecule has four active sites and so can carry four oxygen molecules.

When red blood cells reach parts of the body where oxygen is required the oxygen molecules detach from the haemoglobin protein and diffuse out into the bloodstream and then into the tissues.

The Silent Killer

If carbon monoxide is present in the inhaled air then this will also diffuse through the lung walls and into the blood stream and red blood cells. Because of a quirk of fate (or chemistry if you prefer) carbon monoxide molecules fit into the active sites of haemoglobin molecules very snuggly. The bond formed is much tighter than that formed between oxygen and haemoglobin. As a result carbon monoxide is not released rapidly from the red blood cells. It stays. More and more is collected by haemoglobin molecules with the result that the blood saturates with carbon monoxide and less and less oxygen is carried. Organs and tissues that are crying out for oxygen do not get it. The end result is unconsciousness followed by brain death.

This can occur even though the oxygen concentration in the air is completely normal (about 21%). It is the presence of carbon monoxide that is causing the toxic effect. Not the absence of oxygen or a reduction in its concentration.

Carbon monoxide concentrations of about 1.25% or higher will cause immediate unconsciousness and death within minutes. Lower concentrations don’t cause such immediate effects but they do cause a variety of symptoms that grow progressively worse over time and can lead to the same end result.

The Number of Deaths

The RoSPA website states that there are about 40 accidental fatalities annually in England and Wales (see here). Figures obtained from the Office for National Statistics put the number at consistently over 50 for England and Wales (see here and open the various linked data tables but note that not every data request resulted in a successful release).

Image Courtesy of: Gas Safe Register

Gas Appliances and the Gas Safe Register

One of the principal sources of carbon monoxide involved in these poisonings is poorly installed and maintained gas appliances. If, for example, a gas boiler has not been installed correctly, then carbon monoxide gas produced in the combustion chamber can leak from the installation into rooms.

This is why the Gas Safe register is operated (see here). Engineers and companies that work on gas installations have to be on the register as required by the Gas Safety (Installation and Use) Regulations 1998 (see here and here). This scheme was previously known as CORGI registration.

Image Courtesy of: Gas Safe Register

Recent Reports

I mention this because a couple of recent prosecutions reported in the safety media caught my eye. Both involved gas fitters jailed for unsafe work and for fraudulently pretending to be on the register. These two cases were reported a week apart (see here and here for the HSE press releases).

A quick trawl through the HSE media reports for the last year (June 2018 to June 2019) reveal no less than 15 cases against individuals or companies for similar offences or for other carbon monoxide-related breaches. Mostly involving the Gas Safety (Installation and Use) Regulations 1998, but some involving breaches of HSWA.

Since I had to look at all of the press releases I might as well pass the links on – so here are the rest of them for you: 1,   2,   3,   4,   5,   6,   7,   8,   9,   10,   11,   12,   13

That is just over the last 12 months.

They make for rather repetitive reading.

It would be easy to become cynical.

Other Databases

A similar trawl through the HSE’s public register of prosecutions (yes there is such a thing!) (available here) reveals a similar number of prosecution records from the last 12 months.

If you haven’t looked at this database of prosecutions then have a go. You have to use drop down boxes to select your search criteria to get the results. Try BREACHES > REGULATION > Gas Safety (Installation and Use) Regulations 1998.

And note that there are two databases – one for the last 12 months and one for historic prosecutions older than 12 months (see here).

A trawl through the HSE public register of enforcement notices (no I am not making any of this up!) (available here) reveals that over 110 individuals or companies had improvement or prohibition notices served on them under the Gas Safety (Installation and Use) Regulations 1998 in the last 12 months.

Again, if you haven’t looked at this database it’s worth a play just for fun. As before, use the drop down boxes and try REGULATION > Gas Safety (Installation and Use) Regulations 1998. It should throw up all of the notices issued over the last 5 years under the regs.

Now try searching for friends and family just see what they have been hiding from you for all these years.

Again there are two list available; one for the last 5 years and one for 5-10 years (see here).

And Finally Ronnie…

So the next time you have someone round to do a bit of work on your boiler just cogitate on the facts above. At work or at home. And check them out on the register (see here).

Image Courtesy of: Gas Safe Register

And the next time you check into a hotel room, or into a rented flat, house or apartment cogitate on a bit more (and remember this).

And if you get a bit of a headache and start to feel a bit nauseous, perhaps with some cold and flu like symptoms, then stop cogitating and do something about it (see here).

And buy yourself a CO alarm.

£20 and it could save your life.

Dr Jim Phelpstead BSc, PhD, CMIOSH

RRC Consultant Tutor