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The great laughing gas mystery is no laughing matter for the Southern District Health Board, which has still not uncovered why it uses so much nitrous oxide.
A carbon footprint assessment of the SDHB last year uncovered the surprising statistic that Southern, despite its small population, used vastly more nitrous oxide than expected.
An investigation was started of pipework in Dunedin Hospital, in the expectation it would reveal a leak of the gas used for anaesthetic and pain relief purposes.
The audit did not show up any problems, specialist services executive director Patrick Ng told an SDHB hospital advisory committee meeting yesterday.
"We have also checked the outlets and done some washer replacements at the same time," Mr Ng said.
Staff would now look at whether equipment hooked up to the pipe work was working correctly, he said.