Climate Change and Allergies


Controversial topics, anyone?

Actually, the evidence that the Earth is warming is not that controversial.  You can see direct and indirect evidence in numerous places.  Whether you choose to believe that this is a man-made phenomenon or just another global cycle or both is not the topic of this post.  Rather, I’ll touch on some of the changes occurring in pollen seasons that have been documented over the last decade or so.

Wind pollinated trees, grasses, and weeds dominate the world of outdoor allergies.  The timing of their pollination, called bud-set and flowering, is often linked with accumulated warmth over time.  Thus, as the Earth warms, we should see earlier pollination for many plant species and, indeed, we have.  Over the last decade, a shift to earlier pollination has been documented for such predominant allergens as  birch in Northern Europe, olive and parietaria sp. in Southern Europe, and ragweed in the U.S. and Canada.  Not only have these seasons started earlier, but they have also lasted longer- a double whammy for allergy sufferers.

In addition to earlier and longer seasons, climate change is likely to affect pollen levels for certain plants.  Pollen counts are largely determined by the number of plants in an area, called biomass, and the recent weather patterns in that area.  In the U.S., there have been documented increases in biomass for both pine and ragweed, while in Europe, higher total pollen counts have been seen for birch, olive and parietaria sp. in their respective regions.

This is all bad news for allergy sufferers.  With continued climate change, we can expect to see even longer, more intense pollen seasons resulting in more misery for the individual and a much greater burden of disease for our population as a whole.  As a correlate, we can expect to see a shift towards more intensive therapy for the individual allergy patient and greater utilization of specialty care for the population.  As always, your local board-certified allergist remains the best option for managing difficult to treat allergies and their complications.

Dr. O

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