Yearly global emissions of anaesthetic agents can be compared with that of carbon dioxide emissions from one million cars or one coal-fired power plant, says a study.

The chemists studied widely used anaesthetics agents such as isoflurane, desflurane, and sevoflurane and their potential impacts on climate.

All three are worse than CO2... desflurane the most harmful will cause 1620 times as much global warming as an equal amount of CO2, says Ole John Nielsen, Professor of atmospheric chemistry at the University of Copenhagen.

The mildest ones Isoflurane and Sevoflurane have global warming potentials of 210 and 510 respectively.

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, says Nielsen.

The study could be used to accurately evaluate the climatic impact of activities that involve the use, and release to the atmosphere, of halogenated anaesthetic agents, chemists say.

The chemists estimate that around 200 million anaesthetic procedures are performed worldwide on an annual basis.

Global climate change is caused mainly by higher atmospheric concentrations of the major long-lived greenhouse gases CO2 and halogenated organic compounds.

The study was carried out by chemists from University of Copenhagen and NASA in collaboration with anaesthesiologists from the University of Michigan Medical School.