Hay fever heyday

Bright flowers of the moojar tree or West Australian Christmas Tree (Nuytsia floribunda), which flowers from October to January.

The beginning of November marks the midway point of Spring and the Noongar season of Kambarang (birth). It’s the time of year known for an explosion of colour and a proliferation of flowers, but for many people, these flowers also bring hay fever and a greater risk of respiratory issues.

According to Dr Ivan Hanigan, Curtin University Senior Lecturer in Climate Change and Health and Director of WHO Collaborating Centre for Environmental Health Impact Assessment, data collected by the recently established Perth Pollen appears to show Perth’s grass pollen season peaks at the end of October and early November.

Perth Pollen is a grass seed forecasting service operated by a network of universities across Australia, including Curtin University, to provide a daily forecast of the amount of pollen present in the air. Although the primary focus of the service is grass seeds, it detects a wide range of pollen present in the air.      

Dr Hanigan also said, “Pollen levels are highest later in the evening in Perth,” Which varies from pollen observations in the eastern states.

Associate Professor Paul Beggs at Macquarie’s School of Natural Sciences said plant pollination seasons in Australia appear to be changing, with some plants beginning to produce flowers earlier in the season and others producing flowers for an extended period, which has resulted in a greater amount of pollen present in the environment for a longer period of time.

AsthmaWA educator Eleissa Fuller said an increased exposure period to pollen could lead to intensified symptoms for people with asthma and hay fever. These intensified symptoms can be irritating, like frequent sneezing, having a runny nose or far more life-threatening.

Ms Fuller said that one in nine Australians manage asthma on an ongoing basis, and one in five Australians manage allergic rhinitis (hay fever).

Dr Hanigan said, “We know that allergy rates are on the rise. Recent studies have shown that increasing pollen exposure can heighten vulnerability to respiratory viral infection, including SARS-CoV-2.”

According to Professor Beggs, the increased level of plant pollen produced and changes to the pollination season are due to changes within the climate, with increased atmospheric carbon dioxide and higher temperatures playing significant roles.

He also said climate change has resulted in the southward migration of subtropical grasses in the eastern states, contributing to increased environmental pollen.

The severity of climate change in Australia is affected by climate variability forces. Specifically, Professor Beggs said, “El Niño will magnify what we are seeing with climate change.”

The Bureau of Meteorology said much of Western Australia will receive less than average rainfall over the next few months, and the chance of unusually warm temperatures is double the normal.

Looking at Perth, this means daytime temperatures have an 80% chance of being over 26.6˚ C in November and 29.5˚ C in December.  while Perth’s rainfall is forecast to have a 30% chance of exceeding 25.3 mm in November and 9.9 mm in December.

Credit: The Australian Bureau of Meteorology

Several factors, including Global warming, higher ocean temperatures, and Australian climate drivers, impact this forecast. The climate drivers include El Niño and the positive Indian Ocean Dipole announced by the Bureau of Meteorology earlier this year.

In addition to the impact of an extended pollen season, Dr Hanigan said, “Bushfires, dust storms and hot, dry conditions are likely to exacerbate health issues and not just respiratory diseases but heart disease too.”

The latest Australasian Fire And Emergency Services Authorities Council Seasonal Bushfire Outlook for Spring 2023 suggests the southwest of WA will see increased surface fuel availability in late Spring, making  Bushfires challenging to suppress and the hot dry conditions will impact planned burning opportunities.

Climate variability phases like the current El Niño and the positive Indian Ocean Dipole generally last for between twelve months to a few years. However, these forces are also changing due to climate change, which makes looking at the Australian climate system complex, according to Professor Beggs.

In addition to the changing environmental conditions, Australia lags behind the research completed in the northern hemisphere. However, a large amount of research is underway to help science in Australia understand how the Australian environment is changing and the impact this has on the pollination cycle.

This research includes programs like Perth Pollen, launched at Curtin University last year as part of a national network. Since its launch, Dr Hanigan said the program has shown how Perth’s pollen levels differ from the eastern states and helps people with asthma plan their day and reduce the risk of asthma attacks.