Environment Protection Agency

A Review of the Impact of Climate Variability and Change on Aeroallergens and Their Associated Effects (Final Report)

This report is a survey of the current state of scientific knowledge of the potential impacts of climate change and climate variability on aeroallergens in the United States -- including the impacts of pollens, molds, and indoor allergens -- and their associated effects on allergenic illnesses. 

Since 1998, EPA has been assessing the consequences of global change on weather-related morbidity, on vector- and water-borne diseases, and on airborne allergens and ambient pollutants, especially tropospheric ozone and fine particles. With this completed, this report adds to the increasing body of knowledge on potential effects of global climate change on human health.

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Allergies and allergy-related illnesses are widespread in the U.S. and impose substantial economic and quality of life burdens. Changes in climate, including increased CO2 concentrations, could impact the production, distribution, and dispersion of aeroallergens; allergen content; and the growth and distribution of the weeds, grasses, tress, and mold that produce them. While the literature does not provide definitive data or conclusions on how climate change might impact aeroallergens and subsequently allergenic illnesses, some tentative conclusions can be drawn:

Pollen production is likely to increase in many parts of the U.S. with the possible exception of the Southeast;

Phenologic advance is likely to occur for numerous species of plants, especially trees;

There will likely be changes in the distribution of pollen producing species, including the possibility of extinction in some cases;

Intercontinental dispersal is possible, facilitating the introduction of new aeroallergens into the U.S.; and

Increases in allergen content of some aeroallergens are possible.