The average carbon footprint of a single nitrous oxide — commonly known as laughing gas — sedation appointment is 28.6 kilograms of carbon dioxide equivalent (kg CO₂e), equal to a 72.8-mile journey in a gasoline car, according to a study by the UCL Eastman Dental Institute at University College London.
Researchers analysed data from 891 episodes of inhalation sedation collected from 31 dental services across 128 primary and secondary care sites in the UK. The findings were published Feb. 27 in the British Dental Journal.
The study is the first to quantify the environmental impact of nitrous oxide use in dentistry across different care settings in the UK.
“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,” said first author Alexandra Lyne of the UCL Eastman Dental Institute. “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 standardizing practice where possible. By doing this, dental services can reduce emissions while maintaining patient care.”
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273 times more potent than carbon dioxide
Nitrous oxide has a global warming potential 273 times greater than carbon dioxide.
At the service level, the carbon footprint linked to one week of clinical nitrous oxide use ranged from 38.9 to 1,849 kg CO₂e — the latter equivalent to 4,709 miles driven in a gasoline car, based on U.S. Environmental Protection Agency conversion figures.
Most participating settings used individual cylinders to supply nitrous oxide, while a smaller proportion relied on central gas delivery systems. Average wastage was 30 per cent higher in settings using piped systems compared with cylinder-based systems, though variation was observed across both.
Inhalation sedation remained highly effective, with 92 per cent of procedures successfully completed. Eighty-three per cent of patients were children or young people, for whom inhalation sedation is the only standard sedation option available.
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‘More gas than they actually need’
The study also found wide variation in delivery practices, with flow rates ranging from one to 13 litres per minute and no clear link to patient age.
“Our analysis showed wide variation in how nitrous oxide is delivered,” said contributing author Professor Paul Ashley. “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.”
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Some services reported routinely using inhalation sedation for acclimatization visits involving simple, non-invasive procedures. However, researchers found no meaningful difference in success rates between services that offered acclimatization under sedation and those that did not, raising questions about the environmental cost of this practice.
The research team recommends auditing gas use and wastage, minimizing flow rates and duration of administration, reviewing routine sedation for acclimatization visits, and considering alternatives where appropriate. They also call on professional bodies to incorporate environmental considerations into future dental sedation guidelines and urge further research into wastage and clinical administration practices.