In 2019 the board discovered, as part of work to establish what its carbon footprint was, that it used vastly more nitrous oxide than any other district health board.
Medical gases such as nitrous oxide were the second largest contributor to the SDHB’s carbon footprint, and at 12.6%, were higher than both electricity and vehicles.
At that time the board was using 3432 tonnes of nitrous oxide as a pain reliever, about 20 times more than any other DHB.
Cylinders used at Dunedin Hospital accounted for 3171 tonnes, but Southland used just 165.
The revelation sparked a major audit of gas use at Dunedin Hospital and close examination of the hospital’s pipes.
All were pressure tested but none showed any leaks, SDHB chief executive Chris Fleming said.
"However, testing of some of the wall outlets in our operating theatres suggested they may be leaking, so they replaced all the seals in the wall outlets in theatres."
That work seemed to have solved the problem, he said.
"Usage has significantly decreased with 56 cylinders being used in 2020 compared to 308 in 2016.
"This resulted in a massive reduction in nitrous oxide usage of approximately 2600 tonnes — about the same as a Toyota Corolla driven 15million kilometres."
The board would now expand the outlet tests to other locations.
"We now are using nitrous oxide at a level that puts us in the middle of the road compared to other DHB, whereas we used to be a complete outlier," Mr Fleming said.
"We owe a debt of gratitude to Dr Matt Jenks, who has spent a considerable amount of personal energy getting to the bottom of the problem."
The board was also working on converting its coal boilers at both Dunedin and Southland Hospitals to wood biomass, Mr Fleming said.
"The two biggest carbon challenges we have had are the boilers, and the nitrous oxide use, so it will be a great achievement if we can eliminate both of these."
