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Ask The Expert

March 5, 2014

Climate Change Effects on Allergy


I am an allergist in a small community and I have been invited to be part of a panel on a TV current events program to discuss the effects of climate change on allergy in the community. I am aware of some data on the earlier start and prolonged nature of seasonal pollens. Is there good evidence of other changes we can expect?


From the Editors: Climate change is a hot topic, not only in the general community, but within the community of allergists. We are fortunate to have three experts who have given us a brief overview of climate change and allergy, in response to a submitted question.

By Prof. Nelson Rosario

Climate changes may influence negatively seasonal allergies for several reasons: plants can grow faster and produce more pollen; the content of allergenic material is increased as well; Bud set and flowering are intimately linked to accumulated warmth for many herbaceous and woody plants. Anthropogenic global warming speeds flower development, resulting in earlier blooming. Pollen season starts earlier and may be longer than usual. Symptoms of asthma and rhinoconjunctivitis will therefore be more severe and more prolonged because of interaction between heavier pollen loads and increased air pollution.

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By Dr. Leonard Bielory

In the Northern Hemisphere, the balance of evidence strongly suggests that a significant impact of climate change is already discernible in animal and plant populations, as well as communities and ecosystems. Climate changes include advancement of phenological spring events, such as flowering by 6 days and delay of autumn events by 5 days, compared with the early 1960s; climate changes on aeroallergens with increased pollen production from exposure to increased CO2 concentration; increased pollen to local rises in Temp; increased allergenicity in pollen from trees grown at increased Temp; phenological trends toward earlier pollen seasons are associated with local warming over the latter decades of the 1900s that have demonstrated earlier pollination (0.84 days per year) of trees more than grasses or weeds and globally longer pollination seasons.

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By Dr. Gennaro D’Amato

Global temperature has risen markedly over the last 30 years due to increases in greenhouse gas emissions, largely from anthropogenic sources. For example, mean annual central England temperatures have continued to rise and are now over 2° C higher than in the coldest period of the “Little Ice Age” in the late 17th century with half of this increase occurring in the last 40 years. The increase in temperature has also seen a rapid rise in the number of hot days and severe meteorological events such as the 2003, 2012 and 2013  heat wave where temperatures of 35°C and greater were reached resulting in around forty thousand excess deaths across Europe.

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