By Wendy Tuohy
An increase in the length of Melbourne’s pollen season due to the effects of climate change will likely cause more incidents of weather conditions that produce potentially deadly thunderstorm asthma, researchers say.
Melbourne is already the allergy capital of the world, with government data showing about 31.8 per cent of residents experience allergic rhinitis. A significant cause is pollen inhalation, and new data shows the city’s annual pollen season is starting earlier and lasting longer.
Researchers have found Melbourne’s pollen season is starting earlier and lasting longer.Credit: Luis Enrique Ascui
This could mean more days prone to thunderstorm asthma conditions, when winds and coinciding electrified storms pull large amounts of pollen into the atmosphere. Melbourne is also the global capital of thunderstorm asthma, a condition that caused 10 deaths in 2016.
University of Queensland scientists analysed three decades of airborne pollen data in Melbourne, Sydney and Canberra and found that though an eight-year drought had reduced the pollen concentration slightly through the research period in Melbourne, the pollen season was extending.
Sydney and Canberra experienced big overall pollen increases, at 34 per cent and 200 per cent respectively.
Public health associate professor Nicholas Osborne said Melbourne’s core pollen season, which usually runs from mid-October to the end of December, was changing in duration as spring rain patterns shifted, elevating maximum grass pollen numbers.
Grass pollen from perennial ryegrass, which grows widely around the city fringes, combines with a particular type of storm front to which Melbourne is prone to cause thunderstorm asthma, which can hit even those who have not previously had the breathing condition.
“Our research suggests in future there’s probably going to be more grass pollen around and more tree pollen, and we want … to be able to make some sort of prediction so we can better plan for public health,” Osborne said.
“About 10 per cent of people suffer from asthma, and 30 to 40 per cent have some sort of rhinitis and we need to be able to predict it.”
Osborne’s team has also been researching why Melbourne is comparatively more likely to produce thunderstorm asthma, when cities such as Sydney have more storms. “It is the combination of dry, windy days over a population centre where the population has allergies,” he said.
“The Australian population seems to be one of the most allergic populations around the world.”
Melbourne University environmental epidemiologist Dr Rachel Tham is part of a research team examining a potential link between being prone to pollen-induced hay fever and experiencing thunderstorm asthma, given far more people affected by Melbourne’s worst outbreak had previously had hay fever than regular asthma.
“We’re aiming to recruit people across Melbourne who have hay fever and want to identify among those people if they have a certain biomarker which identifies them as being at risk of asthma when grass pollen levels change,” said Tham.
“If we can predict those people, we can get them onto asthma prevention at the start of the season rather than waiting for them to have an attack.”
Researchers are studying a possible link between hay fever and thunderstorm asthma as Melbourne’s pollen season, fuelled by grass and tree pollen, is now longer.Credit: Louis Enrique Ascui
Dr Jonathan Pham, consultant allergist at The Alfred hospital and researcher at Monash University School of Translational Medicine, said the influence of climate change on pollen allergy was concerning because Australians were already vulnerable to adverse pollen effects.
“Allergy to pollen has led to increased emergency department visits for asthma and, in severe cases, fatalities,” he said.
“This was tragically demonstrated during the 2016 Melbourne thunderstorm asthma epidemic, which was triggered by extreme grass pollen levels and resulted in 3365 emergency presentations and 10 deaths.”
He said chronic – persistent or ongoing – impacts were equally profound. “Pollen allergies and asthma can hinder childhood development, causing lifelong morbidity from reduced participation in school, sports and social activities.”
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