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Increased ambient temperatures over land and increased ground-level carbon dioxide concentrations, both of which are expected with climate change, result in increased plant metabolism and pollen production. These factors may also be associated with increased fungal growth and spore release.

Pollen and mold spores are allergens and can aggravate allergic rhinitis and several respiratory diseases, including asthma and chronic obstructive pulmonary disease, though the latter diseases have other significant triggers. Allergic diseases are the sixth leading cause of chronic disease in the U.S. and impose a substantial burden on the U.S. population. Asthma alone affects approximately 20 million Americans. Some experts have suggested that the global rise in asthma is an early health effect of climate change.

Aeroallergens act with other harmful air pollution to worsen respiratory disease. While the magnitude of climate change’s impact on allergic disease in the U.S. is yet to be determined, preliminary evidence suggests that there could be a substantial effect.

Additional Information about Aero-allergens

CDC Air Pollution and Respiratory Health Page