Airborne Pollen Grains Facilitate the Spread of COVID-19 by Carrying SARS-CoV-2 Particles

Computer models simulating the movement of pollen grains from trees in crowded areas could accelerate the spread of COVID-19.

Tree pollen. Image Credit: Elisa Manzati / Shutterstock.com

Pollen particles as a new infectious agent

The general understanding of viral infection focuses on how viral particles escaping from a person to infect a nearby person. However, other infectious agents are also important to consider when including the role of the environment.

Early in the COVID-19 pandemic, researchers developed models to explain the high rate of COVID-19 infection and found that viral particles are able to last on surfaces for a long time, facilitating the spread of the virus. .

New research now shows a new environmental agent that has not been considered before. Published in the Physics of Fluids Journal, authors Talib Dbouk and Dimitris Drikakis studied how pollen facilitates the spread of an RNA virus like the COVID-19 virus.

The researchers used computer model simulations to examine the role of microscopic particles in virus transmission.

The hypothesis was first developed when researchers observed a correlation between rates of COVID-19 infection and pollen concentration on the national allergy map. Previous studies have already shown that trees can produce 1,500 grains of pollen per cubic meter in the air on heavy days and that each grain of pollen carries hundreds of viral particles at a time, but no one has yet considered a such infectious spread in crowded areas.

To our knowledge, this is the first time that we have shown by modeling and simulation how airborne pollen micrograins are carried in a light breeze, contributing to the transmission of viruses through the air in crowds to the ‘outside’,

Drikakis

Dynamic environmental agents could limit the effectiveness of social distancing measures

The researchers simulated all of the pollen-producing parts of a computer willow tree in a public space of an outdoor gathering of about 10 or 100 people, some of them releasing COVID-19 particles, and submitted people with 10,000 pollen grains.

The models were then tuned for a typical spring day in the United States in terms of temperature, wind speed, and humidity, all of which can affect pollen transport.

Simulations then showed that it took less than a minute for pollen grains to pass through the crowd surrounding the tree, which could spread the virus quickly and easily, infecting new individuals even when they are socially distant.

Even when a distance of 6 feet was maintained between individuals, it was not a sufficient distance to limit the risk of the disease spreading in such an area with a high concentration of pollen in the air.

The authors therefore recommend basing preventive measures such as distancing on seasonal factors to better manage the risk of infection. Adapting measures such as social distancing in areas known for high pollen concentrations in spring could therefore mitigate at least some infection risks.

Further studies will refine the simulations, especially whether specific trees, areas or viruses are more or less likely to be transported.

One of the big challenges is to recreate a completely realistic environment of a mature willow tree. This included thousands of tree leaves and pollen grain particles, hundreds of stems, and a realistic gathering of a crowd of about 100 individuals about 20 meters from the tree. “

Dbouk

Although this study primarily demonstrates a new form of Transmission of covid-19, the authors also hope to stimulate further studies on plant fluid dynamics and the interaction between airborne pollen grains and the human respiratory system under different environmental conditions. Nonetheless, this study is the first to show a new method of infection by airborne virus transmission and is particularly insightful when designing adaptive preventive measures for the current global pandemic.