The connection to climate change
Dr. Cassie Irwin
Are you more sneezy than you used to be? There may be a connection between seasonal allergies and climate change. Scientists are learning about how our changing climate is affecting the onset, duration, and intensity of seasonal allergies. But what does that mean for your annoying sneezing and itchy eyes?
Pollen allergy has grown increasingly prevalent in recent decades. While this can be attributed to a few different factors, what’s becoming increasingly clear is the connection between seasonal allergies and climate change. If you’ve noticed that your seasonal allergies have aggravated you more over the years, or if you’ve developed new allergies in adulthood after being scot-free for most of your life, the research suggests that climate change could be in part to blame.
The rising temperature and increased humidity we’re seeing with climate change favour longer growing seasons for the weeds and plants that trigger seasonal allergies. And it seems that the longer growing season is creating a vicious cycle; when exposed to warmer temperatures and higher levels of carbon dioxide, plants grow bigger and produce more pollen than their typical yield. Our rising sea temperatures have contributed to more frequent thunderstorms, during which plants release pollen in great quantities. Thunderstorms are understood to be an important cause of increasing seasonal allergic rhinitis and asthma attacks. Air pollution itself independently impacts levels of allergen sensitivity, dependent on location and air quality. Taken together, these mechanisms of climate change are increasing both the quantity of pollen in the air, as well as its allergenic potential. The World Allergy Organization predicts that climate change will continue to affect the onset, duration, and intensity of the pollen season in years to come.
Biodiversity loss may be a considerable factor in the increased prevalence of allergy and inflammatory disease in developed countries. As habitats change and wildlife is threatened, the resulting reduction in biodiversity weakens the environment’s microbiome, and accordingly, the human microbiome. Research has shown that school-aged children living on a farm had exposure to a more diverse microbiome and had a lower prevalence of allergic disease compared with their urban counterparts. And, as city dwellers have less interaction with richly biodiverse environments and physical contact with trees, plants, and soil, their immune tolerance mechanism becomes impaired. Immune tolerance is a key function in the immune system, which, when impaired, can present as either seasonal allergy, food allergy, or autoimmunity. Research suggests that exposure to rich microbial environments is correlated with reduced prevalence of allergy and autoimmune disease. Never has “tree-hugging” been such an evidence-based prescription!