Climate change could affect grass pollen seasons, and your hayfever

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The sneezin’ season in the northern hemisphere might be prolonged due to climate change, and scientists want to know what that could mean for asthma and hayfever sufferers in Australia.

Both the length of the hayfever season and the amount of pollen north of the equator is on the rise, according to a study published in the journal Lancet Planet Health earlier this year.

And it’s higher temperatures that are responsible for these changes.

Plane tree in autumn colours in front of blue sky
Plane tree pollen is major problem for many people with asthma and allergic rhinitis prior to grass pollen season. (Getty Images: Jenny Dettrick)

While such dataislacking across the southern hemisphere, it’s possible the same trend is occurring in Australia, according to Paul Beggs, study author and environmental health scientist from Macquarie University.

“We have temperature and CO2 increases occurring here, so one would assume that this is happening in places like Australia,” Dr Beggs said.

“This is really important for a place like Australia where the prevalence of allergic respiratory disease — things like asthma or hay fever — is so high.”

The research from the northern hemisphere highlights another link between ongoing global warming and public health that could worsen as temperatures continue to rise, and scientists say Australia is lagging behind.

Potential pollen changes down under

The effects of climate change on different types of pollen in Australia are likely to be more complex than in the northern hemisphere, Dr Beggs said.

“If you had a severe drought in a particular location, then you’d expect less pollen and less vegetation growth,” he said.

“But in Australia we go from one extreme to the other, so even if we’re moving into a drier climate generally, there will still be years that are particularly wet that we need to look out for.”

Short-term pollen data from around Australia suggests there is a lengthening of the pollen season, and that pollen is increasingly abundant, according to Simon Haberle, a professor of natural history.

“We need to know whether this is going to be a long-term trend or is it just a random event,” said Professor Haberle from the Australian National University.

He said another unknown is whether plants with allergenic pollen — like rye and bahia grasses — will move into new areas as the environment changes.

“A few new plants being planted by people or migrating in the environment can shift how risky a city or an area might be relative to hayfever and asthma,” Professor Haberle said.

Close up of pollen on the ragweed plant, a common allergen in the northern hemisphere
Ragweed could become a bigger problem for allergy sufferers in Australia, as it has in Europe. (Getty Images: Elenathewise)

Parts of Europe are already experiencing this with the introduction of ragweed. The number of people sensitised to its pollen is projected to double in the next couple of decades.

“The numbers really blow out in Europe at least for that species, so that’s going to have massive public health consequences,” Dr Beggs said.

“One of the questions in my mind is: what does the future hold for Australia in terms of species like that?

“Will we cross over some threshold where species like that start to take off and spread?”

And it’s not just pollen patterns that are changing with the climate — other allergenic plants, as well as stinging insects and fungi spores will likely be impacted too.

Australia’s monitoring compares ‘poorly’

Australia is particularly vulnerable to changes in pollen because of our high rates of asthma and allergic rhinitis, especially in areas like Canberra and Melbourne.

This underlying vulnerability was highlighted by the world’s worst thunderstorm asthma event that took place in November 2016 in Melbourne.

Taking into account the environmental conditions that led to the event, and considering climate change, Dr Beggs thinks it could happen more frequently.

“There’s a lot of research showing that increases in CO2 in the atmosphere make some pollen grains more potent, increasing allergenicity,” he said.

Microscopic image of a grass pollen grain.
The pink blob is many people’s worst enemy come mid-late October — a grass pollen grain. (Supplied: Ed Newbigin)

While the 2016 thunderstorm event spurred significant investment in pollen monitoring in Victoria, Dr Beggs is concerned the lack of long-term data and ongoing pollen monitoring nationwide is putting Australians at risk.

“It’s a massive public health problem,” he said.

“With a changing climate and a very high prevalence of these [allergenic] diseases in Australia, we are left very vulnerable.

“It should be a national responsibility, but at the moment we are comparing very poorly to other developed countries in terms of continuous long-term monitoring.”

Currently, there is ongoing pollen monitoring at several stations acrossSydney, Canberra, Brisbane and Tasmania, and seasonal monitoring across Victoria.

This year’s grass pollen season

Victorians should prepare for a worse grass pollen season than last year, according to botanist Ed Newbigin from the University of Melbourne.

Pollen forecast information:

  • Victoria, Australian Capital Territory, Queensland and New South Wales residents can use the Pollen Forecast Network websites or download the state-specific apps for pollen forecasts.
  • Tasmanians can access pollen forecasts from the AirRater app.
  • There are not currently any pollen monitoring networks in South Australia, Western Australia or the Northern Territory.

“The 2019 season is looking like it will be worse than 2018 for hayfever sufferers, as far as grass pollen allergies go,” Dr Newbigin said.

“Although it has been quite dry this year, there’s been good late autumn and winter rainfall.”

Surveys of soil throughout the state reflect this, showing average to above average levels of moisture, which is what drives grass growth.

“Based on current conditions, the grasses are in pretty good health across Victoria, which is great news for farmers of wheat and barley, but the downside is the grass pollen is worse than last year,” Dr Newbigin said.

He added that people should not base their hayfever or asthma management on what happened last year, as it was a low-pollen year.

Satellite image showing vegetation growth
Victoria has experienced more vegetation growth this year compared to last, which probably means a worse grass pollen season. (Supplied: NASA/USGS)

Canberrans,on the other hand,should be able to breathe slightly easier thanks to the dry weather the region has experienced all year, Professor Haberle said.

“It certainly looks drier than previous years, so we’re anticipating it might be less of a severe grass pollen year,” he said.

However, tree pollen is still an issue for people with asthma and hay fever.

“Trees in the urban landscape tend to be more resilient to drought, mostly because they get watered, so it is quite a severe tree pollen year,” Professor Haberle said.