The Pollen Problem


We hear a lot about the negative effects of climate change. Rising sea levels will continue to threaten coastal communities. Extreme weather events like heat waves, droughts, and storms of all kinds will become more common. Air and water pollution are harming the health of humans and animals alike. But there is another way climate change is impacting human health – allergies. 


According to the CDC, allergies affect around 60 million Americans, many of them suffering from pollen allergies. That’s a lot of people. And according to multiple studies, climate change is making allergies worse in two ways. 


The first is that climate change is causing spring to arrive earlier in places that have distinct seasons like New England. An earlier spring means earlier blooms which means pollen will be in the air sooner. But it’s not just pollen from the trees you can see that are causing your allergies. According to John J. Costa, MD, Medical Director of the Allergy and Clinical Immunology Practice at Brigham and Women’s Hospital, pollen can be carried by wind to Massachusetts from as far away as Ohio. That means if spring starts earlier in places to our south, pollen season can start here in Boston even if spring hasn’t. 


The other way that climate change is affecting allergies is by increasing the amount of pollen plants produce. According to multiple studies, elevated levels of CO2 in the air cause plants to produce more pollen. 


One 2018 study published in the International Journal of Biometeorology tested pollen production in oak trees that grew in three chambers with increased ambient CO2. The first chamber had CO2 levels of 400 ppm, which is currently average for outdoor air. (For context, the level was 280 ppm pre-industrial revolution.) The second chamber had a level of 560 ppm, and the third, 720 ppm. The trees growing in chambers two and three showed pollen level increases of 353% and 1299% respectively, compared to chamber one. At the current rate of emissions, CO2 levels will be at 550 ppm by 2050 and 950 by 2100.


Some studies even suggest that the levels of allergy inducing proteins in the pollen increase with elevated CO2. It all leads to worsening allergies for those who are allergic. So, no, you’re not just imagining that recent allergy seasons have been worse than usual. But you can count on more of the same in the future. 




Written by Adam Doucette 4/25/2022


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