The Impact of Pollen and Allergens on Health

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Climate change may generate higher pollen and allergen concentrations and for longer periods of time, which will affect the health of more people.  Pollen is an airborne allergen and its grains are tiny “seeds” that are dispersed from flowering plants, trees, grasses, and weeds.  The amount and type of pollen in the air depends on the season and geographic region.  Although pollen counts are usually higher during warmer seasons, some plants pollinate throughout the year.


Climate change could lead to changes in rainfall patterns, warmer seasons, and more carbon dioxide (CO2) in the atmosphere.  These changes can affect: when the pollen season begins and ends, and how long it lasts each year, how much pollen plants create and how much is in the air, how pollen affects our health (the “allergenicity” of pollen), how much pollen we are exposed to, and our risk of experiencing allergy symptoms.


Exposure to pollen can trigger various allergic reactions such as rhinitis, which occurs when allergens such as pollen enter the body and the immune system mistakenly identifies them as a threat.  If you have allergic rhinitis, your body responds to the allergen by releasing chemicals that can cause symptoms in your nose.  Symptoms of allergic rhinitis may occur during certain seasons or year-round, depending on the allergen.  Symptoms of allergic rhinitis include sneezing, runny nose, and congestion.


Another symptom of pollen exposure is allergic conjunctivitis.  This is inflammation of the lining of the eye (conjunctiva) due to exposure to allergens such as  pollen.  Symptoms include red, watery, or itchy eyes.


People with respiratory diseases such as asthma may be more sensitive to pollen.  Pollen exposure has been linked to asthma attacks and increased hospital admissions for respiratory diseases.  Higher pollen concentrations and longer pollen seasons can also make you more sensitive to allergens.  This can trigger asthma episodes.


Extreme rainfall and rising temperatures can also contribute to indoor air quality problems.  For example, they can cause indoor mold growth, which can lead to worsening respiratory conditions for people with asthma and/or mold allergies, and greater challenges in maintaining adequate asthma control.





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