Comment: It creeps up on us every year and then hits with a vengeance. It’s pollen season, the plague of hay fever sufferers everywhere. With signs climate change may be increasing the amount of pollen in the air, can we expect to be hit harder this year?
Over the past few decades, rates of hay fever, asthma and related allergies have been getting worse and we don’t know why. Changes in pollen levels won’t be the only answer but as pollen is one of the principal allergy triggers, it’s an obvious place to start.
In many parts of the world, airborne pollen is routinely monitored to provide forecasts for allergy sufferers and medical practitioners alike and to track changes in the allergy load in the air we breathe.
But New Zealand lacks this essential service. Instead, we rely on information from previous monitoring efforts, coupled with current observations of which plants are flowering at the time.
Both these methods have their problems.
Flowering observations don’t tell us how much pollen is being dispersed into the atmosphere and can be deceptive. For example, the brazen extroverts that seduce our senses with colour and fragrance are hard-wired for attracting birds and insects to spread their pollen to a specific target.
These plants don’t waste their energy producing shed-loads of pollen to be dispersed far and wide by the wind. It’s the unremarkable introverts, with their innocuous, unappealing flowers, that we have to look out for as they pack a double punch: producing pollen in vast numbers and also tending to have the strongest allergenic properties.
The problems with the other method we’ve relied on—using old data from past pollen monitoring programmes—should be easier to fix.
The last rigorous pollen monitoring in Auckland, and for that matter nationwide, was way back in the summer of 1988/89. Back then, I trudged up the white stone steps of the hidden spiral staircase that leads to the roof of Auckland’s War Memorial Museum to install a pollen monitoring trap. This year, I’m helping colleagues from Auckland and Massey universities to repeat the exercise, sampling the airborne pollen in Auckland from precisely the same museum rooftop.
What might have changed in the past 35 years? Not much, we might think? Apart from the occasional interloper (such as the giant hypodermic needle protruding from the CBD), the vista from the museum rooftop seems much as I recall from all those years earlier, at least in terms of pollen sources. The city’s iconic landmarks, from the Auckland Domain to the Waitakere Ranges, remain clothed in their distinctive vegetation.
But as with the showy flowers, we are deceiving ourselves to think that those pollen sources, types and amounts have remained unchanged. Climate and land use changes, new introduced plants, even atmospheric carbon dioxide levels—the engine fuel for photosynthesis—all will have affected the pollen loading in Auckland’s atmosphere to varying extents that we can only know by measuring.
Four months into our monitoring programme, our preliminary results suggest the pollen seasons may well be changing.
Take grass pollen for example—the biggest culprit for hay fever sufferers. A direct comparison between our 2023 results and data from 1988 shows the grass pollen season began three to four days earlier this year and the number of days with high grass pollen—when most hay fever symptoms are triggered—increased by at least 75 percent.
Of course, we can’t be sure that this year is typical of current times based on a single snapshot like this, but these are precisely the sort of shifts that might be expected from the climate changes observed over the past 35 years. To be sure that the timing and severity of pollen seasons are shifting, we need to keep this work going and monitor the pollen for successive years.
Two of my colleagues on this project, asthma specialist Dr Amy Chan and optometrist Dr Stuti Misra, both researchers at Auckland University, have noticed increased asthma and eye disorders amongst their clinical patients during springtime. They are therefore keen to know if these problems coincide with higher levels of pollen.
That’s one of the questions our research aims to shed light on. Will these asthma and eye disorders coincide with peak pollen levels and with the usual suspects—typically the grasses in the spring? Will we find new allergenic sources, or maybe old familiar culprits popping up at different times? Has the timing of the pollen seasons shifted earlier as you might expect from warmer temperatures and has the volume of airborne pollen increased overall, in line with increased allergic response, since the last time we bothered to look?
So many questions. Helping us find the answers that may be blowing in the winds are Dr Kat Holt, like me a palynologist (the official term for people who analyse pollen and can trace it back to the source plant), and two research students from Auckland University, Laura McDonald and Natasha Ngadi, who are doing most of the pollen monitoring work.
This article was originally published on Newsroom.
Rewi Newnham is a professor of Physical Geography and head of the School of Science in Society at Te Herenga Waka—Victoria University of Wellington.