Impacts of Storm Type, Seasonality, and Mesoscale Dynamics on Pollen Dispersion and Fragmentation

Pollen and other air particulates cause allergy symptoms in almost 24 million people per year in the US. Global warming is making this worse, as it is lengthening pollen seasons and worsening pollen-pollution interactions which increases their allergenicity. Wind-dispersed (anemophilous) pollen grain sizes that induce allergic rhinitis symptoms range from 20 to 40 microns in diameter. While the basic constraints of anemophilous pollen dispersion are known, the role of meteorological events is less well-understood. In thunderstorms, rain can decrease pollen and other debris concentrations in the air and limit dispersion, and moisture can also rupture pollen grains and create pollen fragments. This process, known as fragmentation, results in smaller pieces of pollen with diameters ranging from 2.5 to 0.25 microns. Particulates smaller than 10 microns are a hazard to health, as they are not filtered out by the nose and can penetrate deep into the lungs. Here, we record pollen, air quality, and meteorological data from two locations (Ithaca, NY and Houston, TX) to ensure results from a diverse array of storm types. In addition to taking direct observations, we combined synthesis with existing records, real-time monitoring, and numerical modeling to understand how air particulate concentrations change over the duration of different storm events. Results indicate that the seasonality as well as other storm characteristics (e.g. origin, convective cloud height, synoptic scale dynamics, and land-atmosphere moisture coupling) affect pollen and particulate matter dispersion patterns. Based on our initial results, we hypothesize that large storms with mature circulation (strong downdraft) result in more pollen fragmentation and particulate dispersion. The outcomes of this research will have positive implications for public health and safety, as being able to inform people which storm events create hazardous air quality conditions will reduce outbreaks of allergy symptoms and thunderstorm asthma.