As evidence continues to accumulate regarding the effects of climate change, its influence on health outcomes has become the focus of greater attention. Increased flooding and variation in rainfall patterns, for example, can affect freshwater supplies and increase the risk for water-borne and vector-borne illnesses; air pollution has been shown to exacerbate cardiovascular disease.1
In addition, various effects of climate change have significant implications for respiratory diseases, as described in a report1 by Jeffrey G Demain, MD, FAAP, FACAAI, FAAAAI, director of the Allergy Asthma & Immunology Center of Alaska in Anchorage; clinical professor, Department of Pediatrics at the University of Washington in Seattle; and affiliate professor at the University of Alaska, Anchorage.
Changing Pollination Patterns
Evidence suggests that higher temperatures and ambient carbon dioxide (CO2) levels “increase pollen load, prolong pollen seasons, and intensify allergenicity in studied weed and tree pollens,” wrote Dr Demain. “Moreover, as the climate changes, plant species may adapt and undergo shifts in demographic distribution, expanding the zone of some allergenic plants.”
Studies have shown that elevated CO2 concentrations may increase ragweed plant pollen production by 30% to 90%, induce earlier plant flowering, and increase its primary allergenic peptide, Amb a 1.
Extreme Weather and Rising Sea Levels
It is anticipated that extreme weather events resulting from climate change will increase respiratory morbidity and mortality.1 Greater incidence of flooding and rising sea levels threatens to increase exposure to indoor moisture and mold, thus exacerbating or increasing the risk for respiratory disease. According to a meta-analysis of 33 epidemiologic studies, occupants of damp, moldy homes experienced a 30% to 50% increase in adverse respiratory health outcomes.2 Climate-driven increases in moisture and mold are expected to especially affect the 3.3 billion people worldwide who reside in coastal regions.1
Concentrations of ground level ozone (O3), which is “generated at ground level by photochemical reactions involving nitrogen dioxide (NO2), hydrocarbons, heat and ultraviolet radiation,” have increased since preindustrial times, wrote Demain, et al.1 Exposure to O3 has a “direct impact on the human respiratory system, increasing the frequency of asthma exacerbations, increasing susceptibility to infection, and promoting chronic obstructive pulmonary disease (COPD).” In a study published in 2013, patients with asthma showed an increased allergic response to birch pollen when exposed to increased levels of O3.3