Allergy season is around the corner, and likely to be harsher in some parts of Canada than others.
And as the climate continues to warm, spurring more pollen production, that’s only going to get worse, experts caution.
A study released this week by Aerobiology Research Laboratories suggested that pollen seasons are becoming “more intense overall.”
“You cannot escape allergies if you live in Canada; it’s impossible,” said Daniel Coates, director at Aerobiology Research Laboratories.
The study reported that “annual pollen loads across Canada show a clear overall upward trend despite year-to-year variability.”
As individual seasons fluctuate, the trendline indicates a steady increase in total airborne pollen, suggesting that “pollen seasons are becoming more intense overall.”
Coates said Canada has seen a doubling in pollen in the last 25 years.
“Pollen loves warm temperatures. It loves warm weather. This is how it reproduces itself, to fertilize,” he said.
“So, when you have longer periods of warmer weather, which we are getting statistically now, you’re having more pollen in the air as well.”
Health Canada states that research has shown that “climate change will increase allergens in the air and related allergic diseases as warmer weather and milder winters can result in increased pollen production in plants.”
“More frequent thunderstorms may also put more pollen into the air. Furthermore, higher carbon dioxide levels, due to climate change, can increase plant growth and pollen production.”
Coates described climate change as the “catalyst” for why pollen has doubled so highly.
“Pollen is being released in warm weather, and as you have longer seasons of much warmer weather, you’re going to have more pollen flying in the air and so that’s a direct correlation.”
“Unless we dramatically change the environment, it’s only going to continue to get worse.”
Allergy researcher Dr. Amin Kanani also stated to the University of British Columbia earlier this year that “warmer temperatures and higher CO2 levels are leading to longer growing seasons and more plant growth, because plants use CO2 as their fuel to grow.”
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“With more plants there’s more pollen being produced — studies show that pollen seasons are becoming longer, and peak pollen counts are getting higher. People should expect to experience earlier and longer pollen seasons,” he said in the university’s information page about why allergies are getting worse.
Dr. Mariam Hanna, pediatric section chair for the Canadian Society of Allergy and Clinical Immunology, says the past 20 years have displayed a pattern where spring is starting earlier and fall is starting later.
“Those that have seasonal allergies or are sensitized and have symptoms to those various pollens, the longer those pollens are out, the longer their symptoms will stay,” she said.
Although allergy symptoms can vary from one person to another, Hanna also noted that the amount of time someone spends outside will help dictate how severe symptoms will be.
“We do see the more exposure that you have to that particular pollen, the more systems you have,” she said. “So not because that you have environmental allergies that we necessarily expect each year is going to be exponentially worse for you. But if the counts are higher and the counts up longer and you’re spending time outside, then you’re going to be more symptomatic.”
The Aerobiology Research Laboratories study found that five Canadian cities are the “most challenging Canadian cities for seasonal pollen allergies”:
- Windsor, Ont.
- Hamilton, Ont.
- Barrie, Ont.
- Victoria, B.C.
- Kingston, Ont.
This was determined by the number of days “with high or very high airborne pollen concentrations and the length of the season for the most clinically relevant allergenic plant species, including trees, grasses, and weeds.”
Hanna said that “pollens will travel for quite a large distance,” but the condition of natural forests and the environment in a region dictate how severe symptoms can be.
“We know that certain areas where that plant matter is more ubiquitous to that environment or that forest type is more common, people that are impacted by those allergies will have more symptoms,” she said.
Meanwhile, the top five best Canadian cities for seasonal allergies were found to be:
- St. John’s, N.L.
- Saint John, N.B.
- Regina, Sask.
- Moncton, N.B.
- Halifax, N.S.
Coates also explained why certain Canadian provinces experience harsher seasonal allergies.
“Ontario is going to be the worst, British Columbia will be second, then Quebec, Alberta, Manitoba, Saskatchewan and then the Maritimes,” he said.
“The main difference with Vancouver and Victoria is because they have the longer season, they’re at the top of the charts for grass pollen because their season starts earlier and it’s milder weather.”
Coates also stated that high levels of pollen exist in both rural and urban areas in Canada despite assumptions that would not be the case.
“Cities love to plant male trees simply because female trees produce fruits and flowers,” he said. “Those rot fall to the ground and then make a big mess, so usually that’s another way that we see more pollen in the air is because they’re planting male trees that release pollen.”
Coates also said that pollution plays a role in making allergy symptoms more intense.
“Because pollen likes warm weather, you’re going to see longer seasons because of that. But pollution also breaks down pollen, and what that does for allergy sufferers is it actually allows pollen to get deeper into their lungs, making their allergic reactions more severe,” he said.
“For those reasons, you might not see necessarily as much pollen in a downtown core. But you’re going to see the effects of it definitely for allergy sufferers in the downtown core as well as rural and suburban areas.”
Canada is experiencing a late start to allergy season this year thanks to the extended cold weather this spring. The peak of allergy season is expected to hit in the middle of May.