Rising CO2, climate change and allergies

Over 300 million people suffer from asthma worldwide, and another 400 million from allergic rhinitis (AR), commonly known as hay fever. How will these allergies change as the climate changes? We already know that pollen seasons, drivers in airborne allergens, are prone to changing when temperatures and conditions change—how will individuals with these allergic diseases be affected when they do so? Significant costs are already associated with asthma and AR, with respect to medical treatment and lost work days, beyond the effects to quality of life. In this paper, Dr. Lew Ziska lays out this dynamic between climate change and allergies, as it is already playing out and as it is expected to worsen.

Increasing carbon dioxide in the atmosphere leads to warming on the surface of Earth, which is happening at different rates at different parts of the planet. It is predicted that this will yield longer fungal allergen seasons, earlier pollen seasons, and northward shifts in where these allergens are found. Shifts have already been observed: in Europe, common ragweed, a pollen source, has expanded its geographic range. In other studies, pollen concentrations have increased significantly with temperature and precipitation. Of course, these biological changes through climate change play out on an existing social landscape. Dr. Ziska notes that socioeconomic factors may determine the extent to which mold, another allergen, can be managed in cases of flooding or other wet weather events. Man-made factors such as air pollution also cause asthma and other respiratory issues themselves, not to mention the compounding dynamic between particles from exhaust and pollen.

What about clinical effects? Studies have found a correlation between peaks in spring tree pollen and allergy medication sales and emergency hospital visits for asthma. Other studies have matched allergy patterns to pollen counts, heat waves and earlier spring to cases of hay fever. Dr. Ziska points to the critical areas of need in further understanding the dynamic between allergies and climate change. In addition to more clinical trials, we need a better understanding and more robust analysis of pollen or spores that lead to airborne allergens, a consistent standard for pollen collection, and infrastructure for the monitoring of these allergens. Furthermore, as wildfires and other extreme events throw our models for understanding these dynamics into question, we must maintain a commitment to developing research that fits our changing world.

Ziska LH.
 An Overview of Rising CO2 and Climatic Change on Aeroallergens and Allergic Diseases. Allergy Asthma Immunol Res. 2020 Sep;12(5):771-782.

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