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People living near New Zealand's natural hot springs may think the rotten-egg smell in the air is associated with health benefits, but it could be harmful.
And then there's the stink from sewerage farms ...
It's hoped a new $4 million study will determine the long-term impact of exposure to low levels of hydrogen sulphide, the gas that causes the smell.
A joint New Zealand and United States study will focus on Rotorua, the tourist spot famed for its sulphur hot springs, and check the impact on 2000 locals.
Tests will evaluate the health of their lungs, nerves and eyes, among other things.
About 52,000 people live in Rotorua city, the largest permanent population of people who live near a hotspring anywhere in the world.
Professor Julian Crane from the University of Otago said the cause of the stink near the springs was hydrogen sulphide, a poisonous gas that in high levels can kill people in seconds.
In February 2000, a tourist died at Rotorua after exposure to high levels of the gas, and other deaths have occurred at hotsprings in other parts of the world.
Crane, who is helping to conduct the five-year study, said it was not known whether long-term low concentrations of the gas were also dangerous, or could have health benefits.
"No one has ever thought it (low-level exposure) is particularly unhealthy, and there isn't a folklore either that says it is a big problem," he said.
He said his study would have widespread implications for people living in areas like the Melbourne suburb of Werribee, where sewerage farms produce large amounts of hydrogen sulphide.
Pulp mills also create a lot of the gas and it was necessary to know whether there were health and safety implications for workers, he said.
Crane said he doubted whether bathing in hotsprings had any special health benefits other than the effect from bathing in warm water.
"Whether or not it is hugely healthy, it is pretty jolly nice," he said.
Mayor Kevin Winters from Rotorua District Council said indigenous New Zealanders had lived locally for 700 years without any apparent ill effects from the gas and he did not expect the study to turn up any health risks.
"Some people think there could be health benefits. We have a lot of elderly people here ... a side-effect could be longevity," he said.
Winters said that after living in Rotorua for some time locals did not notice the rotten egg smell.
"I think it is a very healthy smell," he said.
- AAP
