Canberra has experienced its worst pollen season on record, with scientists warning extremely high pollen levels could continue into next year.
ANU professor and co-creator of Canberra Pollen app Simon Haberle said the 2021 grass season was incredibly intense for hayfever sufferers.
"[It's been] a really extraordinary pollen season. Right through October and November and now into December, we've seen a whole range of our records broken," he said.
This included 20 extreme days recorded in 2021 as of Monday, December 6 and the record grass daily count on November 17.
The season had also been very long, Dr Haberle said. It started in early October and could continue into January next year.
"Normally, we expect it to start to decline through mid-December to Christmas, but we're anticipating that quite elevated levels will persist through Christmas," he said.
"I think we'll be seeing elevated levels of grass even into January. So it really means that we're going to have a really extended grass pollen season this year and into the early part of 2022."
Dr Haberle said the high grass pollen levels had been caused by wet weather.
High rainfall in winter persisted into spring, creating high soil moisture. La Nina over summer meant more rain, helping grass continue to grow.
"We still see green grass around Canberra; that's quite unusual for this time of year," Dr Haberle said.
ANU researchers will be studying whether pollen seasons in years to come could continue to get stronger and longer.
"We think the impact of climate change will be that it actually creates a longer pollen season. And perhaps, in many cases, a stronger pollen season," Dr Haberle said.
Canberra's tree pollen season was also stronger than usual this year. It began in July and lasted until the middle of October.
"That was a whole range of different three species that people are allergic to, and they had quite high values," Dr Haberle said.
People were allergic to tree species including cypress, olive, pine, elm, birch, poplar, oak and plane. The cypress pollen season lasted from early July until late October this year.
Dr Haberle advised hayfever sufferers to monitor the Canberra Pollen website and app.
