Pollen rupturing by Elizabeth Stone

Stone, Elizabeth

Faculty/Staff/Researcher

Chemical and Biochemical Engineering

Atmospheric chemistry

2019-06-22

2020 submissions

Central Microscopy Research Facility, Iowa City, IA

It has long been believed that rainfall washes pollen from the atmosphere, reducing allergen exposure and relieving sufferers of allergies and respiratory disorders. However, pollen grains can rupture in the air to release hundreds of pollen fragments less than 2.5 µm in diameter. Compared to intact pollen grains, pollen fragments can penetrate deeper into the human respiratory stem, persist longer in the atmosphere, and be transported longer distances by wind. Captured here is a 60 µm diameter pollen releasing its cytoplasmic material as it ruptures following a thunderstorm on May 18, 2019. Our research provides the first in situ characterization of pollen fragments in the atmosphere. We show a significant increase in pollen fragments with diameters 0.25-1.0 µm coincident with precipitation during the springtime tree pollen season. Peak pollen fragment concentrations occurred during convective thunderstorms with strong downdrafts, high rates of rainfall, wind speeds, and lightning strikes, although lightning is not required for their release. After the storm, pollen fragments persist in the atmosphere for several hours. Our results contradict the commonly-held belief that rainfall washes pollen allergens out of the atmosphere: on the contrary, they demonstrate peak exposures to pollen fragments occur during and after rain events. Better understanding the environmental conditions that lead to high levels of pollen fragments in the atmosphere can help to protect susceptible populations from exposure to unhealthy allergen levels.

Lillian Jones, Josh Van Stippen, National Science Foundation (AGS 1906091)

2nd place in the 2020 Faculty/Staff/Researchers Category

pollen
fragments
atmosphere

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University of Iowa. College of Engineering. NEXUS Program
University of Iowa. Lichtenberger Engineering Library
Virgil M. Hancher Auditorium

Attribution-NonCommercial 2.0 (CC BY-NC 2.0) https://creativecommons.org/licenses/by-nc/2.0/

Contact Kari Kozak in the Litchenberger Engineering Library at the University of Iowa: http://www.lib.uiowa.edu/eng/contact/

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