Workplace exposure: N20

Nitrous oxide exposure and neurological problems

Added: January 2018

Hospital or dental staff that work in areas where nitrous oxide is administered to help relieve patient pain could be at risk of developing neurological problems, according to several studies.

Nitrous oxide is a colourless and odourless gas commonly known as laughing gas. It is a powerful analgesic in sub-anaesthetic concentrations and is most commonly used as a 50:50 mix with oxygen, typically known as Entonox.

This neurological damage caused by nitrous oxide has been given a variety of names by researchers over the years, including Anesthesia paresthetica, Cobalamin Deficiency Syndrome or Postoperative dementia.

Whilst neurological damage from Nitrous Oxide is rare, when it does occur it can lead to a range of worrying symptoms from forgetfulness and fatigue to megaloblastic anaemia, degenerative lesions on the spine and even death.

It has been noticed that people with a vitamin B12 deficiency are particularly susceptible to neurologic deterioration following nitrous oxide anaesthesia.

This is because Nitrous Oxide effectively renders this important vitamin inactive, preventing it from helping with two important biochemical reactions in the human body. What’s more, every time Nitrous Oxide is administered, vitamins B12 levels are further diminished.

In some cases, people unsuspected of having vitamin B12 deficiency have developed subacute combined degeneration of the spinal cord following nitrous oxide anaesthesia.

Sadly, if a B12 deficiency goes unrecognized, the neurologic deterioration becomes irreversible and may result in death.

Although patients with B12 deficiency are clearly at risk, the same can be said for medical or dental staff that administer Entonox regularly as part of their job, particularly midwives, hospital staff working in Accident & Emergency, Critical Care, Endoscopy, Paediatrics, dentists and dental nurses.

That is because, although Gas and Air is inhaled through a demand valve by the patient, when they exhale, some of the Nitrous Oxide is released back into the room, putting staff at risk of prolonged exposure where rooms are poorly ventilated.

Protecting staff from N2O exposure

The best way to ensure that your staff are not exposed to hazardous levels of Nitrous Oxide is to carry out workplace exposure monitoring.

This will help you comply with the Control of Substances Hazardous to Health regulations which require you to monitor and record staff exposure to Nitrous Oxide against Workplace Exposure Limits set out by the Health & Safety Commission.

Workplace exposure monitoring can be carried out easily by attaching a personal sampling tube to staff clothing near the breathing zone for the duration of a shift. This tube is then analysed and a report produced from the findings.

If hazardous levels of exposure are detected, you can then address the problem and bring exposure levels down to permissible levels.

Of course, in addition to personal sampling, it is also a good idea to carry out good housekeeping on an ongoing basis. This can include keeping Entonox equipment well-maintained to help prevent the risk of leaks and ensuring that any ventilation or scavenging systems are working properly.

For information on Cairn Technology’s personal sampling service for Nitrous Oxide just call 0845 226 0185 and ask for our workplace monitoring team or email them at