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Global Warming and Allergies

Climate Change and Allergic Disease

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Updated October 24, 2012

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

Global warming is a hot-button issue in today’s political environment. Some say that global warming, due to the man-made increases in greenhouse gases, is responsible for melting the polar ice caps and warming the oceans—the result being freakish weather patterns such as hurricanes and tsunamis, all referred to as climate change. Others say that climate change is an inevitable cycle that the earth goes through every thousands to millions of years, and that it has nothing to do with the actions of man. Regardless of your philosophy or political affiliation, there are definite changes to the earth’s climate, which may in part be responsible for the significant increase in allergic diseases in the past few decades.

An increase in global temperatures, rainfall and greenhouse gases promotes the increased growth of various plants (such as trees, weeds and grasses), as well as molds. Increasing pollen and mold spore counts, brought on by longer and more pronounced pollen and mold seasons, will likely lead to increased sensitization to those with atopy, and increased allergy symptoms in those who already suffer from allergic diseases.

Global Warming and Allergic Rhinitis

Evidence of climate change over the past 40 years has coincided with a dramatic increase in allergic rhinitis incidence in the United States population: a rise from 10 to 30 percent. Similar increases have been seen in other westernized countries such as Canada, and based on predictions on the continued rise in global temperatures, the rate of allergic rhinitis is expected to increase by 40% in Japan by 2050.

Climate change has led to an increase in temperatures and rainfall, which in turn results in pollen seasons that occur earlier, have higher peak pollen and mold spore counts, and last longer than expected. This increase in pollen and mold spore counts leads to worsened allergic rhinitis symptoms in affected people, and could result in the development of asthma in susceptible people.

Global Warming and Atopic Dermatitis

While sun exposure and warm weather are generally helpful for the symptoms of atopic dermatitis, climate change could result in the worsening of those symptoms. High temperatures, associated with high humidity, often result in an increase in sweating—well known to worsen the symptoms of atopic dermatitis. In addition, an increase in pollen and mold spore counts, for the reasons outlined above, could result in worsened symptoms of itching, causing more symptoms of eczema in people with atopic dermatitis.

Global Warming and Asthma

There could be many affects on asthma as a result of climate change. Generally, warmer weather is associated with fewer asthma exacerbations, as viral respiratory tract infections are less likely to occur during this time. But the increase in pollen and mold counts, as well as higher pollutant levels associated with global warming, are all likely to cause worsening of asthma symptoms in affected people. The worsened allergic rhinitis symptoms that occur with climate change may also make an impact on asthma symptoms.

Many studies have shown that, with increases in average daily temperatures, there have been increases in the rate of asthma and asthma symptoms. Emergency room visits for asthma have also been shown to increase on days when pollen and mold counts are higher. Asthma exacerbations also occur on days after thunderstorms, which are known to cause pollen grains to release allergenic particles as a result of increased moisture and static charge in the air.

Read about how pollen counts can help you plan your outdoor activities.

Source:

Hidalgo-Dapul G, Bielory L. Climate Change and Allergic Diseases. Ann Allergy Asthma Immunol. 2012;109:166-72.

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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