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 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. Aeroallergens include pollens, which can be produced by weeds, grasses, and trees, as well as molds and other indoor allergens.
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. 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.