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Trees spread COVID-19 through pollen

Most models for viral transmission focus on humans spreading viruses that infect other humans. However, other factors may also be at play when it comes to transmission of viruses like the one that causes COVID-19, including tree pollen.

Researchers noticed a correlation between the increase of pollen and an increase in COVID-19 infections. In a new study from the American Institute of Physics, Talib Dbouk and Dimitris Drikakis set out to investigate how pollen distribution may assist in the spread of SARS-COV-2 and other viruses.

The experts used a computer model to show how pollen moves in a willow. The computer model recreated a realistic tree producing pollen amidst a gathering of roughly 100 people, some of which were infected by COVID-19. 

“This included thousands of tree leaves and pollen grain particles, hundreds of stems and a realistic gathering of a crowd of about 100 individuals at about 20 meters from the tree,” explained Dbouk.

As the tree pollen was caught in the wind and spread through the crowd of people, some of the particles attached to COVID-19 particles, carrying them farther than they would have traveled alone. 

Every grain of pollen can carry hundreds of virus particles, and a tree can populate a cubic meter of air with 1,500 grains on some days. The research suggests that pollen could have a significant impact on virus transmission, changing normal human to human dynamics.     

“In the case of high pollen grains concentrations in the air or during pollination in the spring, the social distance of 2 meters does not hold as a health safety measure for an outdoor crowd,” explained the study authors. “Thus, the public authorities should revise the social distancing guidelines.”

Although this study focused mainly on COVID-19 transmissions, the researchers hope that the paper increases interest in fluid dynamics of trees. 

They plan on carrying out more research on how these dynamics affect human respiration under different atmospheric conditions next.    

The study is published in the journal Physics of Fluids.

By Zach Fitzner , Staff Writer

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