by Catarina Chagas, Queen's University

Credit: CC0 Public Domain

Colorful flowers and delicate blossoms on trees are not the only sign that spring has truly arrived. For many, allergies are a sign the seasons have changed. Up to one in four Canadians suffer from allergic rhinitis and its symptoms—runny nose, sneezing, itchy/watery eyes, and occasionally coughing. With climate change, the problem might be getting more intense: experts believe increased greenhouse atmospheric concentration and higher temperatures cause plants to have longer flowering seasons, which leads to more pollen in the air. Also, seasonal allergies tend to be aggravated by air pollutants like diesel exhaust particles.

Anne Ellis, chair of Queen's Division of Allergy and Immunology and clinical scientist at Kingston Health Sciences Center (KHSC), is paying close attention to how seasonal allergies have changed in the past decade. She has some disconcerting news: it is still hard to distinguish patterns and make assertive predictions.

"Every year is different," she says. "This year's tree pollen season actually started on time compared to 10 years ago, but in more recent past we've had a very late start to tree pollen season, owing to much longer winters."

Changing cycles

While 2021 saw record-breaking levels of birch pollen, so far 2022 has been more typical in terms of overall counts for Southern Ontario. In April, however, warmer days followed by cold nights and even snow brought pollination to a halt.

"Expect the unexpected when it comes to your allergies," is Dr. Ellis' main advice for those reaching for their antihistamines each spring.

But Dr. Ellis believes shortening spring and fall seasons—with longer winter and summer—make a big difference, at least in how people perceive their allergy symptoms.

"We wind up with a longer winter and more time to 'forget' how bad our seasonal allergies can be, so they affect us more dramatically when they come back," she says.

North America is also seeing hotter summers with higher humidity, which can be a challenge for people with asthma. Because humidity fuels dust mite growth, even staying indoors doesn't always provide relief—at least if one doesn't have air conditioning or a dehumidifier.

Some practical tips

Dr. Ellis recommends that people suffering from seasonal allergies keep their windows closed and the air conditioning on when possible, and to avoid hanging clothes on clotheslines outside to prevent pollen capture. Rinsing the nose with a saline solution might help, too.

At local pharmacies, people can look for non-sedating, second generation antihistamines such as cetirizine or loratadine—Dr. Ellis says it's better to avoid older, sedating antihistamines that might have unintended side effects and are not as effective as the new ones. If over the counter medicines are not enough to provide relief, she suggests seeing a doctor for prescription medications such as new antihistamines and intranasal corticosteroids, which reduce swelling and mucus in the nose.

In case these tips don't do the trick, seeing a specialist might be the best option.

"Ask your doctor for a referral to an allergist to be skin tested and find out what you are allergic to specifically," advises Dr. Ellis. "An allergist can offer customized immunotherapy options based on these results that actually treat the underlying allergy, rather than just masking symptoms."

From a public health perspective, Dr. Ellis says urban planning can make a difference, for example, in planting female trees that don't pollinate—while they drop nuts and fruits, which can be messy, they don't cause increases in pollen counts.

Research in action

Dr. Ellis leads the Kingston Environmental Exposure Unit at KHSC. In this facility, she and her team have a meticulously controlled environment that allows them to study the impact of allergens in health at any time of the year.

"The highly controlled indoor environment eliminates the variables of weather, participant environment, and the changing characteristics of seasonal allergens," explains Dr. Ellis. "A proprietary computer-controlled delivery system and stringent monitoring ensure that the levels of allergen maintained in the unity remain within specific requirements."

Since the 1980s, the unit has been used to advance our knowledge of how effective different anti-allergic treatments can be, including antihistamines, nasal corticosteroids and other medications.

Provided by Queen's University