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Yes, your allergies are getting worse. An allergist explains why

Climate change, urban planning and CO2 levels are all affecting allergy season.
Spring and fall are difficult for many Canadians.

Across North America, seasonal allergies are getting worse. Up to 40 per cent of the Canadian population will experience at least one allergic condition in some point in their lives, says Dr. Anne Ellis, a professor and division chair in the department of medicine at Queen’s University.

Ellis says we don’t understand why some people get allergies and other people don’t, but we do know that the frequency of them is increasing. She says there’s some genetic reasoning behind allergies, but that’s not the whole explanation.

Ellis spoke with host Menaka Raman-Wilms on The Decibel podcast about what’s causing this spike in allergies for Canadians.

Menaka Raman-Wilms: I’m excited to talk to you because I have to say, my allergies have been very bad this spring. I keep hearing from other people about how bad their allergies are as well. I mean, do you just hear complaints from people all the time right now?

Dr. Anne Ellis: Well, it’s definitely a busy time of year. We’re in the thick of birch pollen season, which is really the first significant allergen to hit the air, if you will, particularly in Ontario. Nationally, pollen season started back in February in B.C. but for Ontario, we’ve had such a slow, cold spring, it really took a while for everything to take off. And then, of course, when you have sudden warming, that sends a real signal to the trees that, oh, it’s time to get caught up, we didn’t start pollinating yet. So you end up being hit pretty hard when you have a sudden warm up like that.

Are allergies getting worse?

Raman-Wilms: It certainly feels like allergies are getting worse. Dr. Ellis, is there evidence to show that that’s actually the case?

Dr. Ellis: So what’s happening is because we’re having a delayed start to the spring season, tree pollen is just getting up and running. And there used to be a break in between tree pollen season and grass pollen season, which is the next one that will come. Now, there’s more of an overlap. So if people are allergic to both trees and grass, they’re having a much harder time of it. But also in the last two years, we’ve had sort of record pollen count. So that definitely makes the season worse for people who suffer from allergies.

Raman-Wilms: Can you tell me a little bit more about the length of time that pollen is released?

Dr. Ellis: It depends on which pollen we’re talking about. Tree pollen season is anywhere from usually around two to four weeks. Grass pollen season, again, about four to six weeks. The longest season – it only affects the eastern provinces – is ragweed. It starts around Aug. 15 and sticks around until the first good frost in the in the fall. So that’s the longest season. Now, fortunately for people who live west of Manitoba, there’s no ragweed out there yet. So it’s really mostly Ontario, Quebec and the Atlantic Provinces that suffer from ragweed allergy.

Is climate change affecting allergies?

Raman-Wilms: So it sounds like really we’re talking about temperature changes as a big factor here. So I’ve got to ask, is this an impact of climate change and the differences that we’re seeing now?

Dr. Ellis: We are seeing a change in our weather patterns. And it’s that changing, the differences in our season is almost certainly driving some of the changes we’re seeing to pollen seasons.

Raman-Wilms: Ok so climate changes is kind of lengthening the time or changing the time that pollen is around each year. Is that the only thing that’s changing? Is there anything else that’s contributing to to why allergies are so bad?

Dr. Ellis: So there are a couple of things. So particularly we’re talking about trees, so urban planning, they love to plant male plants because the females make fruit and they’re hard to clean up after. And the males plants are the ones that release the pollen. So obviously the female plants are the ones that receive it and they’re pollinated and they make their fruit.

Raman-Wilms: Wow. I never would have thought of that. Male versus female trees.

Dr. Ellis: So that’s contributing to higher pollen counts as well. The other thing that we’re noticing is that we do know that there are probably higher concentrations of CO2 in the air now compared to ten years ago, and higher CO2 levels have been shown to increase the allergenicity of the plants. So that’s contributing a little bit as well.

Raman-Wilms: What exactly does that mean, allergenicity?

Dr. Ellis: How potent it is, if you want to think of it that way. Like how much more likely it is to cause an allergic reaction.

Raman-Wilms: There is a lot of fear around allergy season getting longer and longer, especially when we’re talking about kind of the connection here to climate change, things getting warmer for a longer period of time. What does the future of allergy season in Canada look like?

Dr. Ellis: I think the good news is, is that I don’t think it’s going to change too much from what we see now. We’ve already seen a number of changes in terms of tree pollen season being worse than it used to. I think it’s just important for Canadians to realize that, yes, no one dies of allergic rhinitis, but it does cause a lot of misery. Don’t be afraid to ask your doctor or your primary care provider to send you to an allergist so you can find an allergist and find relief.

Raman-Wilms: Yeah. And I guess in certain parts of the country, we’re always going to have that cold period over winter. So you have that little reprieve, even if the rest of the, you know, spring and fall is difficult.

Dr. Ellis: Exactly. That’s one of the upsides of cold weather.

Dr. Anne Ellis speaks with The Decibel’s Menaka Raman-Wilms about why allergies are getting worse. Subscribe for more episodes.

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