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As climate change spurs more pollen across the country, experts are looking for ways to alleviate the allergenic burden on Canadians

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A haze hangs over downtown Calgary on July 15, 2021.Jeff McIntosh/The Canadian Press

Canadians should expect harsher and more widespread allergy seasons this spring and in the coming years as climate change drives temperatures up and induces pollen-generating plants to overproduce – though experts say environmental and health policy responses can mitigate the suffering.

In 2021, scientists detected a 21-per-cent increase in pollen levels across North America between 1990 and 2018, boding poorly for the 20 to 25 per cent of Canadians who experience seasonal allergies and the 10 per cent who suffer from asthma. Evidence shows that the rise in severe seasonal allergies and asthma, which are linked to climate-driven pollen increases, could cost Canada millions of dollars in business revenue and health care expenses.

There are ways to adapt to this allergenic assault, experts say, including targeting problematic plant life, providing better pharmacare and mitigating climate change.

In many parts of the Northern Hemisphere, the combination of higher temperatures allowing plants to bloom earlier and later, and higher CO2 levels that cause more pollen production, is the driving force behind why allergy seasons are getting worse, says Frances Coates, founder and now-retired CEO of Aerobiology Research Laboratories in Ottawa. For almost 30 years, she oversaw the company’s collection and distribution of data on pollen counts gathered from 30 sites across Canada.

But the Canadian case is unique. Data show the allergy season is indeed getting longer in some parts of Canada, though not quite as consistently as other parts of North America. According to Ms. Coates, while pollen production is definitely up owing to CO2, the migrating tree line is also to blame for the problem.

As higher temperatures creep farther north and the tree line follows suit, pollen is introduced to new areas – meaning an increase in severe allergies and asthma in Northern communities. This is especially the case in Ontario and Quebec, where the tree line is populated by trees that produce high levels of pollen.

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Meanwhile, earlier starts to the blooming periods for certain plants have resulted in an overlap of pollen seasons that aggravates allergic and asthmatic reactions, said Dr. Anne Ellis, a professor in the department of medicine at Queen’s University whose research focuses on the effects of allergenic disease.

For example, in Ontario, tree or birch pollen season typically starts in late April and lasts about two to four weeks, while grass pollen season starts later in May. However, due to climate-driven increases in temperature over the past 10 years, grass has begun blooming earlier, and its pollen season now coincides with that of many of the province’s trees.

“Since lots of people are dually sensitized to both of those allergens, it makes for a really rough spring,” said Dr. Ellis. She worries the increased severity of seasonal allergies will have a huge impact on Canadians’ quality of life, affecting daily functions such as sleep, exercise and work. The economic consequences could also be drastic as more Canadians are required to take sick leave, costing businesses millions of dollars in productivity losses.

Some governments have previously proposed and implemented plans of action, including Quebec, which launched a strategic anti-allergen program in 2015 to combat the unprecedented increase of ragweed pollen in the province. The strategy encouraged the province’s municipalities to prioritize preventing ragweed growth over simply removing it, and focusing their landscaping efforts on urban areas where the plant is known to flourish, including vacant lots and snow dumps.

The plan featured a financial-assistance program for municipalities and public-awareness campaigns on the best approaches to prevention and removal, such as using low-impact herbicides and investing in more frequent mowing and street sweeping.

However, municipalities may not always prioritize these methods because of the strain they put on public-management budgets. Cecilia Sierra-Heredia, a researcher and lecturer on aero-allergens at Simon Fraser University, said that’s what makes provincial programs like Quebec’s especially important in curbing the effects of climate change on allergies and asthma. She added that it is also necessary to strike a balance between public and environmental health in these strategies.

“Budgets and actions need to reflect two things – protecting the workers taking these actions, and protecting the surrounding environment,” she said. “That could mean providing personal-protective equipment for city employees who will be exposed to large amounts of pollen, and using herbicides very carefully.”

Many experts also point to the importance of changing the flora planted in cities. An excess of male trees – which are favoured over female trees because they don’t produce flowers or fruit, making less of a mess for street cleaners – belonging to specific species may also be contributing to an overabundance of pollen in urban areas. Ensuring municipalities are informed about what plants cause residents the most problems will be a key step forward in adapting to heavier pollen seasons, according to Ms. Sierra-Heredia.

For Ms. Coates, important next steps for adaption will also include collecting more data on pollen levels each year to make predictions more accurate – providing governments and other bodies further reason to implement infrastructural changes sooner rather than later.

“As we add more data, our models for the future change quite a bit,” she said, noting that “the upwards trend in pollen has been relatively consistent since we founded [Aerobiology Laboratories] in the seventies” and that having more information makes the models that much more accurate and useful.

On infrastructural changes Ms. Sierra-Heredia said it is crucial they are made specific to the region of Canada they are applied to – and that mitigating climate change itself comes first.

“We can take as many adaptive measures as we want, but if we do not prevent an increase in greenhouse gasses, we’ll constantly be trying to catch up to these planetary changes,” she said. “We need measurable, concrete actions from every government on this,” which includes divesting from fossil fuels, as recommended in the most recent assessment report by the Intergovernmental Panel on Climate Change, she said.

Ms. Sierra-Heredia also noted the importance of adjusting the provincial and federal budgets to account for increases in health care spending related to seasonal allergies and asthma – which Dr. Ellis echoed, noting some provinces still do not cover antihistamines under their pharmacare programs, making treatment inaccessible for many Canadians.

For now, allergy and asthma sufferers should expect to take matters into their own hands. Heeding pollen forecasts, wearing sunglasses or masks outside, and improving the air circulation in homes are all ways in which individuals can adjust to the new extremity of Canada’s pollen season, according to Dr. Ellis.

“In the end, my take-away message is always this – don’t suffer in silence,” she said. “Find an allergist and find relief.”

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