3 December 2010

Anaesthetic gasses heat climate as much as one million cars

Global warming

A new study conducted by chemists from the University of Copenhagen and NASA, in collaboration with anaesthesiologists from the University of Michigan Medical School, reveals that gasses for anaesthesia have a high global warming potential. Results show that one kilo of anaesthetic gas has the same affect on the climate as 1620 kilos of CO2.

When doctors want their patients asleep during surgery they only gently turn the gas tap. But anaesthetic gasses have a global warming potential as high as a refrigerant that is on its way to being banned in the EU. Yet, there is no obligation to report anaesthetic gasses along with other greenhouse gasses such as CO2, refrigerants and laughing gas.

One kilo of anaesthetic gas affects the climate as much as 1620 kilos of CO2. This is shown in a recent study carried out by chemists from the University of Copenhagen and NASA in collaboration with anaesthesiologists from the University of Michigan Medical School. The amount of gas needed for a single surgical procedure is not high, but each year surgery related anaesthetics affect the climate as much as one million cars would, states a report in the respected medical journal “British Journal of Anaesthesia”.

Gasses not equally harmful

Analyses of the anaesthetics were carried out by Ole John Nielsen, a Professor of atmospheric chemistry at the University of Copenhagen, and he’s got an important message for doctors.

Ole John Nielsen
“We studied three different gasses in regular use for anaesthesia, and they’re not equally harmful. All three are worse than CO2 but where the mildest ones have global warming potentials of 210 and 510 respectively, the most harmful will cause 1620 times as much global warming as an equal amount of CO2,” explains Professor Ole John Nielsen.

“This ought to make anaesthesiologists sit up and take notice. If all three compounds have equal therapeutic worth, there is every reason to choose the one with the lowest global warming potential,” he says.

The three anaesthetic gasses isoflurane, desflurane and sevoflurane were studied at the Ford atmospheric laboratories near Detroit, Michigan. Mads Andersen of NASA’s Jet Propulsion Laboratories collaborated on the analyses with Ole John Nielsen who is his former PhD supervisor. He relates how he got the idea for the study while his wife was giving birth.

“The anaesthesiologist told me, that the gas used is what we chemist know as a halogenated compound. That’s the same family of compound as the Freon that was famously eating the ozone layer back in the eighties,” says research scientist Mads Andersen.

We should not be unconcerned 

But the gasses are also related to HFC-134a which is slated to be banned across Europe from January 2011. With a global warming potential some 1.300 times that of CO2, HFC-134a is in the exact same range as the worst of the knock-out gasses. Professor Ole John Nielsen does not believe that the amounts of anaesthetic used warrant a ban. But that doesn’t mean we should be unconcerned.

“The surprising properties of anaesthetic gasses are an important reminder to anyone using any kind of gasses. They really ought to examine the atmospheric fate of them, before releasing them into nature,” says Professor Nielsen.