Call for dentists to reduce unnecessary greenhouse gas nitrous oxide use

Peer-Reviewed Publication

University College London

News Release 27-Feb-2026

Nitrous oxide used for sedating patients during dental appointments has a significant environmental impact, with wide variation in use and wastage across the UK, according to a new study by UCL (University College London) researchers.

Inhalation sedation uses a dose of nitrous oxide, otherwise known as laughing gas, and is an established technique for managing dental anxiety in children and adults.

It has a wide margin of safety and is used frequently during procedures such as fillings, crowns and root canals. However, nitrous oxide is also a potent greenhouse gas with a global warming potential 273 times greater than carbon dioxide.

Researchers at the UCL Eastman Dental Institute analysed data from 891 episodes of inhalation sedation collected from 31 dental services, covering 128 primary and secondary care sites.

They recorded the average carbon footprint per sedation appointment at 28.6 kilograms of carbon dioxide equivalent (kg CO₂e), equivalent to a 72.8-mile journey in a petrol car*.

At service level, the carbon footprint associated with one week of clinical nitrous oxide use ranged from 38.9 to 1,849 kg CO₂e, highlighting large variations in practice across the country. The figure of 1,849 kg CO₂e would cost the same emissions as 4,709 miles driven in a petrol car*.

The study, published in the British Dental Journal, is the first to quantify the environmental impact of nitrous oxide use in dentistry across different settings in the UK.

First author Alexandra Lyne, from UCL Eastman Dental Institute, said: “Nitrous oxide has an important role to play in dental care, particularly for children and young people, but it is also a powerful greenhouse gas. Our study shows that its environmental impact varies widely between services, largely due to differences in how it is supplied and administered.

“Our recommendations include monitoring use, reducing unnecessary wastage and standardising practice where possible. By doing this, dental services can reduce emissions while maintaining patient care.”

When assessing usage, the study found most participating sites used individual cylinders to supply nitrous oxide, while a smaller proportion used centrally piped systems. Average wastage was 30% higher in sites using piped supplies than in those using cylinders, although variations in wastage were observed across both types of system.

Contributing author Professor Paul Ashley added: "Our analysis showed wide variation in how nitrous oxide is delivered, with flow rates ranging from 1 to 13 litres per minute and no clear link to patient age. This tells us that many patients may be receiving more gas than they actually need. 

"Using higher flow rates doesn’t improve the patient experience or treatment outcomes, but it does increase nitrous oxide use and its environmental impact, so there’s a clear opportunity to deliver care that’s just as effective while being more considered and patient centred."

Despite these variations in use and wastage, inhalation sedation was found to be highly effective across the sites included in the study, with 92% of dental procedures using the technique successfully completed. 83% of patients were children or young people, for whom inhalation sedation is the only standard sedation option available.

Some services reported using inhalation sedation for acclimatisation visits involving simple, non-invasive procedures. These are short frequent visits designed for children to make each dental visit positive and build on the experience by exposing the child to different aspects of treatment at each appointment.

However, the study found no meaningful difference in success rates between services that routinely offered acclimatisation under sedation and those that did not, raising questions about the environmental cost of this practice.

The team of researchers, which also included Sarah Ahmad, concluded that while inhalation sedation has clear benefits, particularly for paediatric patients, dental practitioners should take steps to reduce the environmental impact of nitrous oxide use.

They recommend auditing gas use and wastage, minimising flow rates and duration of administration, reviewing the routine use of sedation for acclimatisation, and considering alternatives where appropriate.

They also call for professional bodies to take account of the environmental impact of nitrous oxide in future dental sedation guidelines, and for further research into wastage and clinical administration of dental nitrous oxide use to be conducted.

* Figures taken from the Environmental Protection Agency website