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Allergies Getting Worse?
EPA releases report examining climate change's effects on aeroallergens
Every year around this time it starts: itchy, watery eyes, sneezing, wheezing. With the return of spring comes allergy season. As trees and plants sprout new growth, the pollen count climbs and millions of Americans begin to suffer.
Aeroallergens such as dust, ragweed, pollen, and mold impact half of all Americans, and treatment for allergies in the U.S. costs $21 billion annually. What most Americans probably don’t know is that climate change may increase production and dispersion of airborne allergens.
What is the Aeroallergens Report?
A recently released report by the U.S. Environmental Protection Agency, A Review of the Impact of Climate Variability and Change on Aeroallergens and Their Associated Effects, examines what is known about the impacts of climate change and variability on airborne allergens and associated health effects in the United States.
Aeroallergens include pollens, which can be produced by weeds, grasses, and trees, as well as molds and other indoor allergens. EPA’s report examines the current situation, reviews what is known about climate effects on aeroallergens, describes how research has examined potential health effects, and proposes new research avenues to address existing information gaps.
Quality of Life Burdens and Airborne Allergens
Three major allergic diseases have been associated with exposure to aeroallergens: hay fever, asthma, and eczema. These allergic diseases, by themselves and combined, cause substantial health effects and large economic burdens. The direct medical costs of asthma and hay fever are estimated by the American Academy of Allergy, Asthma and Immunology to be $12.5 billion and $6.2 billion per year, respectively (in 2005 dollars). Other studies estimate the direct medical costs of eczema at $1.2-$5.9 billion per year (in 2005 dollars).
Collectively, the three allergic diseases mentioned above rank sixth for annual expenditures among chronic health conditions in the United States. Beyond the direct cost of medical care are the indirect, but substantial, costs associated with the lost time at work, at school, and play.
Expected Changes in Pollen Seasons, Growth, and Allergenicity
Increases in temperature, carbon dioxide (CO2), and precipitation tend to favor the proliferation of weedy plant species that are known producers of allergenic pollen. Higher levels of CO2 in the atmosphere act as a fertilizer for plant growth. Warmer temperatures and increased precipitation cause some plants to grow faster, bloom earlier, and produce more pollen. Temperature changes are expected to alter allergy seasons to begin earlier and last longer and the distribution of allergenic plant varieties to change over time.
Recent scientific studies also suggest that climate-related temperature changes are expected to increase the potency of airborne allergens. Such changes increase the concentration of pollen in the air, the length of the allergy season and the strength of airborne allergens, and associated increases in allergy symptoms.
Climate change will allow certain allergen-producing plant species to move into new areas, and wind blown dust, carrying pollens and molds from outside of the United States, could expose people to allergens they had not previously contacted. Exposure to more potent concentrations of pollen and mold may make current non-sufferers more likely to develop allergic symptoms.
Future Research
Currently, limited data are available on aeroallergen trends in the United States. Further investigation is needed to understand the response of aeroallergens to climate change, to characterize the role of aeroallergens in allergic disease development, and to estimate the costs to avoid or minimize the health impacts of these allergic diseases. Long-term data on aeroallergens are needed to document changes in aeroallergen production, and to characterize the distribution, content, and potency of airborne allergens.