We are heading into the season of itchy eyes, runny noses and scratchy throats for many hay fever sufferers.
Spring can bring a whole load of unwelcome symptoms, but new research has found that El Niño, a climate phenomenon, could be making Aucklanders' allergies worse.
Scientists analysed data from three Auckland summers, one that was El Niño, another La Niña and one neutral, with the findings revealing patterns that could help predict pollen seasons.
Victoria University of Wellington professor Rewi Newnham told Morning Report it was the first time scientists had been able to link hay fever and the weather phenomenon.
"There's always been speculation that this sort of thing happens, particularly El Niño makes things worse for hay fever sufferers because of the weather conditions that that brings to the north of New Zealand," he said.
Allergy NZ chief executive Mark Dixon joined Breakfast to discuss why some Kiwis are hit harder by seasonal allergies. (Source: Breakfast)
"For the first time, we've been able to actually demonstrate that with real data, and that's because we don't really have routine monitoring going on.
"We've had to cobble together data as best we can and then add to it with our existing new pollen monitoring programme."
Newnham said El Niño brought windy and typically drier, sunnier conditions to the north.
That's the sort of weather that promotes pollen production and pollen release during the pollen season, he said.
"I'm talking about grass pollen here, which is the key pollen allergy trigger.
"Whereas La Niña actually is the opposite. In the north, La Niña tends to bring much wetter conditions.
"Remember back to Cyclone Gabriel summer, the Auckland Anniversary flooding summer, that was a La Niña summer, (which) tends to bring wetter conditions.
"That does the opposite, that tends to suppress pollen production and release, making life presumably a little bit easier for people who suffer from grass pollen allergies."
Newnham said when pollen is in the atmosphere, having been released, rain tends to absorb the pollen, pick it up and wash it out, effectively flushing it out of the atmosphere.
He said if that rain persisted, the pollen would recover.
"If we have two or three rainy days in succession, and especially if we have intense rainfall, then that process continues," he said.
"Effectively, the grass pollen levels just shut down. So, that summer of '88, '89, which was a severe La Niña summer, it started raining around Christmas, New Year and continued through into the early New Year days.
"Normally, January is a very busy season for grass pollen in Auckland.
"But there was virtually no grass pollen for the rest of the month in Auckland, largely due to that rain washout effect."
Newnham said the research was particularly exciting as it opened up the possibility of having longer term predictability.
"At the moment we're in a neutral phase," he said. The predictions are saying, well, we're probably going to go into a La Niña phase by the time the grass pollen season comes around, November,
December, January ... they're giving 60, 70% probabilities, it changes by the day.
"We just have to keep an eye on it, but the point is that once those predictions firm up, then people who suffer from these allergies can start to make decisions in the longer term.
"They can start to think about what they're going to be doing during the school holidays, where they're going to be spending it, whether they should be thinking about some more pre-treatment, pre-emptive treatment or it may not be such a big issue this summer."
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