‘Intense’ pollen season expected in May

While spring took its sweet time to arrive, allergy season has been starting earlier and lasting longer over the past several years, and this May, the country’s foremost pollen experts say it’s going to be particularly severe.

Aerobiology Research Laboratories based in Ottawa gathers pollen and spore samples daily from 30 strategically placed monitoring stations across the country. They use the data to predict the levels of allergens in the air and provide forecasts to the public.

“What we’re predicting right now is an intense spring tree pollen season, and we’re actually seeing that play out in our forecast and our data as well,” says director Daniel Coates.

The cause of this “intense” period is dramatic temperature fluctuations seen over the first quarter of the year.

“What happened this year for tree season is we had a warm weather period in March, and usually what happens is trees love warm weather [and release pollen in warm weather]. But then it cooled for quite a while in early April. And so what that usually does is it stops [pollen release]. It says, ‘Nope, not a good time to be releasing pollen,’ and it stops,” explains Coates.

“So when it warms up again, what you have is sort of like a burst of pollen in the atmosphere and it becomes a little bit more of an intense timeframe.”

Coates says the trees affected by the temperature fluctuations include birch, alder, maple, poplar and oak, and those are the types of pollen that will be most prevalent through May.

For grass and weed pollen later in the summer and towards the fall, Coates says they’re expecting slightly more elevated levels than usual but it won’t be “apocalyptic.”

“Toronto is ragweed heaven. So if you have a ragweed allergy and you live in Toronto, it’s always going to be a horrible time of year for you,” he adds.

Climate change contributes to pollen counts

Coates says over the last 25 years, pollen grain counts in the air have doubled in Canada.

“Back in 1998, 2000, we would get around 450,000 to 500,000 grains per cubic metre per year. Now we’re around a million grains per cubic metre per year in Canada,” he says.

While levels do go up and down year-over-year, the overall levels show an upward trend.

“Pollen loves warm weather. So when you have more warm weather, like we are seeing with climate change, you tend to have longer seasons and more pollen in the air, and our data reflects that,” says Coates.

“It is happening. We are having longer seasons and more pollen in the air … and more intense seasons for allergy sufferers.”

There is a direct correlation between higher temperature levels and higher pollen levels, Coates explains, but weather conditions also play a role.

“In the sense that rain washes pollen out, so when it’s raining you’re not going to have a lot of allergy attacks simply because the pollen’s been washed to the ground and so those different variables affect a daily pollen rate,” he says.

They’re not ‘just allergies’

Allergies cover a wide spectrum in terms of severity from mildly annoying to life-threatening.

While environmental allergies to pollen and spores are usually on the lower end of that spectrum, their effects can be fairly damaging says allergist and clinical immunologist Dr. Mariam Hanna.

“Environmental allergies are not life-threatening, but they tend to be quite debilitating in terms of quality of life. There’s great data to say that it does have an impact — from infants all the way to adults — on your day-to-day functioning during work, during sleep, during school, exam season, your commute, your social activities, your ability to try to eat. And when it affects 20 to 25 per cent of the general Canadian population, it’s a big deal,” she says.

She adds that allergy season is also a difficult time of year for those with asthma or other types of lower airway inflammation.

“So this is the time of year [when] the hay fever sufferers do have symptoms, but also our asthmatics may find it more challenging to control their symptoms. So it’s different from a life-threatening type of allergy where we talk about anaphylaxis to food or venom or drug. However, no less of an issue to address because of how long a season can be and how difficult it is to actually really avoid exposure,” says Hanna.

Some basic measures to mitigate allergies include avoiding outdoor activities during high pollen days and closing your windows on those days as well as using air conditioning and HEPA filters where possible, wearing wrap-around sunglasses and masks if necessary.

“But there’s a limit or a degree that that will make a difference because these are not done 24/7 and with rigor. So very quickly you escalate into what are called ‘medical therapies.’ What are the different medications that we can use to get through this?” says Hanna.

The most common medications for allergies are antihistamine pills, nasal sprays and eye drops.

Hanna suggests avoiding what are called “first-generation” antihistamines — these are the type that usually cause drowsiness and are now considered slightly less safe than second and third-generation antihistamines that do not have a sedating effect.

“We know that there’s long-term harm from using these sedating type antihistamines. They cross the blood-brain barrier, we worry about Alzheimer’s and dementia. They have these anticholinergic side effects. So that’s the warning around that class [of drugs],” she explains.

When it comes to nasal sprays, she says they can be used regularly and tend to be more effective. Salt water rinses are harmless and those with steroids contain a very small amount that is unlikely to cause any systemic harm.

Another course of treatment that can be helpful is immunotherapy or allergy shots, which Hanna says work very well and have been known to have long-lasting effects decades after the initial course of injections.

“So while you’re on the shots and once you get off them, you have less need for medications. You have less symptoms while you’re on them and once you’re off them. So we call it a disease-modifying therapy,” says Hanna.

Hanna says there has been a lot of progress in this realm of allergy medication in the past decade and a significant development is sublingual immunotherapy.

“This is taking the allergen that somebody is allergic to in purified format and in a standardized product, using it as a melt-away tablet under the tongue. So this route of delivery obviously avoids needing to use a needle [and involves] far less doctor visits and time off work or time off school to come to doctors’ appointments,” she explains.

“It’s a therapy that while you start it at the doctor’s office the first day to get observed, you can continue it at home and what they’re able to show is that it has the same kind of benefits as those that were able to come in for shots.”

Hanna adds that while many tend to suffer through allergy season by trying various medications or remedies, it is always best to consult your healthcare provider.

“Many of the medications are available over the counter, but to understand what’s the right combination, what’s the right doses and what’s the right way of approaching the symptoms that you’re having really needs people to have discussions with their healthcare providers,” she says.

“There’s far too much ChatGPT happening and it’s not smart enough yet.”