General anaesthetics fuel climate change, scientists warn

Gases used to knock patients out before they go under the knife are ‘fuelling climate change’ and should be replaced with ‘regional’ anaesthetics, scientists claim

  • Scientists say general procedures that knock out patients are used too often  
  • They are given to patients as a gas but much of it escapes to the environment
  • But less environmentally harmful regional anaesthetics can be given instead  
  • Hip and knee replacements procedures at one hospital shows their potential

Switching from general to regional anaesthetics may help cut greenhouse emissions and ultimately help reduce global warming, a new study claims.  

While regional anaesthetics numb a certain part of the body, general anaesthetics make patients totally unconscious for what tend to be more serious procedures. 

But unlike regional anaesthetics, generals use volatile and environmentally-unfriendly halogenated agents, such as desflurane, or nitrous oxide. 

These greenhouse gases, which can be retained in the atmosphere for up to 114 years, damage the earth’s ozone layer, increasing the risk of global warming and climate change.

At one New York hospital last year, just 4 per cent of hip and knee replacement procedures were done under general anaesthetic, compared to a nationwide average of 75 per cent.

This switch prevented carbon emissions equivalent to thousands of pounds of coal burnt or more than three million smartphones charged, US researchers say. 

The scientists advocate the use of regional anaesthetics, which provide more effective pain relief, have fewer unpleasant side effects and shorten hospital stays. 

Switching from general to regional anaesthesia may help cut greenhouse emissions and ultimately help reduce global warming, indicates a real life example at one US hospital over the course of a year, and reported in the journal Regional Anesthesia & Pain Medicine 

Most regional anaesthesia uses a local nerve-blocking agent along with intravenous sedatives, eliminating the use of halogenated gases. 

What’s the difference between general and regional anaesthetics?  


General anaesthetics put patients to sleep and means they are in a state of unconsciousness.

General anaesthesia is essential for some surgical procedures where it may be safer or more comfortable to be unconscious.

It’s usually used for long operations or those that would otherwise be very painful.

They’re often administered as a gas — nitrous oxide, halothane, isoflurane, desflurane, sevoflurane – or injections.


Regional anaesthesia can be used to numb large areas of the body and means patients don’t have to be asleep.

There are three types of regional anaesthesia: spinal, epidural (usually used to numb the lower half of the body, for example, during labour and childbirth) and regional nerve block, used to block the sensation in a specific part of the body.

With regional anaesthesia, a small amount of an anaesthetic drug is injected near to the nerves that connect a part of the body to the brain.

Every year more than 300 million major operations take place in hospitals around the world, according to the University of Melbourne.  

However, some of the gases uses to induce general anaesthesia are thousands of times more potent than our best-known greenhouse gas, carbon dioxide.

These gases escape into the atmosphere and can spread all over the globe, including to the South Pole. 

‘Following general anesthetics, volatile halogenated agents and nitrous oxide are exhaled by the patient and are also often scavenged from the operating room and released into the atmosphere,’ the research team say in Regional Anesthesia & Pain Medicine. 

‘Very little – less than 5 per cent – of the volatile halogenated gases used during general anesthesia is metabolised by the patient.

‘The remainder is eventually vented into the atmosphere, and although each volatile gas used in anesthesia does differ in its global warming potential, all have some contribution to climate change. 

‘The use of regional anesthesia and the avoidance of volatile inhalational agent use may represent an opportunity for anesthesiologists to reduce greenhouse gas emissions and help prevent global warming.’ 

Co-author of the study, Dr Christopher Wu at the Hospital for Special Surgery, New York, told MailOnline that some patients may prefer general anaesthetics, due in part to some misconceptions regarding regionals, such as a fear of being awake for the procedure. 

In 2009, in the US alone, more than a million hip and knee replacement procedures were carried out, lasting an average of two hours.

If all of these were done under general anaesthetic, that would be the equivalent of 112,000 kg of desflurane and 9000 kg of nitrous oxide released into the atmosphere, according to the authors.

That’s equivalent to greenhouse gas emissions generated by 3,260,000 pounds of coal burned, or 333,000 gallons of petrol used, or 7.35 million car miles, or 378 million smartphones charged.

The Hospital for Special Surgery in New York therefore opted to carry out as many hip and knee replacements as possible using regional anaesthesia in 2019. 

The evidence suggests that regional anaesthesia provides more effective pain relief, has fewer unpleasant side effects than general anaesthesia, shortens hospital stay, and may be preferred by patients

Out of the 10,485 procedures carried out that year, just 4 per cent, or 419 in total, were done under general anaesthetic. 

This percentage is far less than the 75 per cent average under general anesthesia and represents a difference of 7,427 patients for whom regional anesthesia was ‘substituted’ for general anesthesia.

This switch ‘saved’ the equivalent of nearly 27,000 pounds of coal burned, 2,750 gallons of petrol, 60,500 car miles, or 3.1 million smartphones charged, researchers report. 

Making this switch, when feasible, may allow GPs and medical staff to ‘take personal responsibility in the fight against global warming’. 

No definitive data can give a specific contribution of anesthetic gases to the worldwide greenhouse gases.

Unlike general anaesthesia, regionals don’t use volatile halogenated agents, such as desflurane, or nitrous oxide. These greenhouse gases, which can be retained in the atmosphere for up to 114 years, damage the earth’s ozone layer, increasing the risk of global warming and climate change 

However, healthcare systems generally are responsible for around 5 to 10 per cent of the national pollutant emissions, while the anesthetic gases contribute to between 50 to 60 per cent of an operating theatre’s carbon footprint. 

‘Ultimately, the increased use of regional anesthesia for the purpose of decreasing our carbon footprint may initiate discussion of other ways to cut greenhouse gases at a larger level,’ the team say. 

Not all surgical procedures are suitable to being performed under regional anesthesia alone, such as brain surgeries, the researchers admit

The decision to use a specific anesthetic method should also primarily be based on the individual patient and their condition. 

Anaesthetic gases accumulating in the Earth’s atmosphere have been detected as far a field as Antarctica, according to a previous study 

Anaesthetic gases accumulating in the Earth’s atmosphere have been detected as far a field as Antarctica, according to a previous study.  

It has been calculated that desflurane, a chemical used for general anesthesia, has a global warming potential of approximately 3,700 times. 

Global warming potential (GWP) is a measure of how much heat a greenhouse gas traps in the atmosphere up to a specific time horizon, relative to carbon dioxide.   

In England, meanwhile, the health and care system is responsible for an estimated 4 to 5 per cent of the country’s carbon footprint.  

Therefore the government has told hospitals to switch to less-polluting anaesthetic gases as part of a campaign for a ‘greener NHS’. 

It’s planning to switch to less polluting anaesthetic gases, better asthma inhalers, and encouraging more active travel for staff.  

The World Health Organisation (WHO) has called global climate change ‘the greatest threat to global health in the 21st century’ and an increase in temperature and resulting environmental changes may eventually cascade to a direct threat to health.

WHO estimates between 2030 and 2050 there will be an additional 250,000 deaths per year due to climate change.

‘These deaths are predicted to occur due to the impacts of extreme heat, lack of safe water, a decrease in staple foods, and an increase in extreme weather and natural disasters,’ the authors conclude. 

‘Although the extent of the contribution of healthcare-related activities to climate change is uncertain, healthcare professionals do have a responsibility and the means to decrease our carbon footprint by reducing our use and emissions of greenhouse gases.’   

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