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Is Global Warming Affecting Pollen Allergies?


Updated March 09, 2010

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Question: Is Global Warming Affecting Pollen Allergies?
Answer: Possibly. There is much debate as to whether or not there actually is global warming on the earth, and whether this is a man-made or a natural event. If the earth truly is warming, we might expect a “greenhouse” effect, causing the increased growth of plants as well as the pollination of these plants. We might also expect the pollinating seasons of these plants, such as spring and fall, to occur earlier in the year and to last longer.

Three recent studies, presented at a major allergy meeting in February 2010, showed that pollen seasons are occurring earlier in the year, lasting longer, and resulting in more airborne pollen. One of these studies, performed in Italy over a 27-year period of time, also found that the amount of pollen in the air was related to higher daytime temperatures, and resulted in more people with sensitization to pollen. The other two studies, performed in St. Louis, Missouri, showed an increase in the amount of juniper pollen and an earlier and longer oak pollen season in the St. Louis area over a 13-year period of time.

The authors of these studies suggest that climate change or global warming may be the reason for their findings. Certainly, if global warming is a reality, we should expect to see allergy seasons occur earlier and longer than in the past. This may also mean an increase in the amount of people with allergies and the amount of symptoms that a person with pollen allergy has. Worsening of pollen allergies may be another effect of global warming that has yet to be fully recognized.


Ariano R, Canonica G, Passalacqua G. The Possible Role Of Climate Changes In Variations Of Pollen Seasons and Allergic Sensitizations Over 27 Years. J Allergy Clin Immunol. 2010; 125: AB192.

Dhar M, Portnoy J, Barnes C. Oak Pollen in the Midwestern United States. J Allergy Clin Immunol. 2010; 125: AB15.

Johnson RM, Barnes C, Dhar M, Portnoy J. Increase in Midwestern Airborne Juniper Pollen Over 13 Years. J Allergy Clin Immunol. 2010; 125: AB16. DISCLAIMER: The information contained in this site is for educational purposes only, and should not be used as a substitute for personal care by a licensed physician. Please see your physician for diagnosis and treatment of any concerning symptoms or medical condition.

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