COVID-19 risk increases with airborne pollen, study finds
Increased pollen concentrations correlate with higher SARS-CoV-
2 infection rates

Date:
March 9, 2021
Source:
Technical University of Munich (TUM)
Summary:
New research finds that when airborne pollen levels are higher,
increased SARS-CoV-2 infection rates can be observed.



FULL STORY ==========================================================================
When airborne pollen levels are higher, increased SARS-CoV-2 infection
rates can be observed. These results were determined by a large-scale
study conducted by an international team headed by researchers at
the Technical University of Munich (TUM) and the Helmholtz Zentrum
Mu"nchen. Members of high-risk groups could protect themselves by watching pollen forecasts and wearing dust filter masks.


==========================================================================
In the spring of 2020, the outbreak of the coronavirus pandemic appeared
to coincide with the tree pollen season in the northern hemisphere. These observations prompted an international team of researchers to conduct an extensive investigation: The scientists wanted to know whether there is
a demonstrable link between airborne pollen concentrations and SARS-CoV-
2 infection rates.

Pollen is a significant environmental factor influencing infection rates
Under the leadership of first author Athanasios Damialis, the team at
the Chair of Environmental Medicine at TUM collected data on airborne
pollen concentrations, weather conditions and SARS-CoV-2 infections --
taking into consideration the variation of infection rates from one day
to another and the total number of positive tests. In their calculations,
the team also included data on population density and the effects of
lockdown measures. The 154 researchers analyzed pollen data from 130
stations in 31 countries on five continents.

The team showed that airborne pollen can account for, on average,
44 percent of the variation in infection rates, with humidity and air temperature also playing a role in some cases. During intervals without lockdown regulations, infection rates were on average 4 percent higher
with every increase of 100 grains of airborne pollen per cubic meter. In
some German cities, concentrations of up to 500 pollen grains per cubic
meter per day were recorded during the study -- which led to an overall increase in infection rates of more than 20 percent. In regions where
lockdown rules were in effect, however, the infection numbers were on
average only half as high at comparable pollen concentrations.

Airborne pollen weakens immune response High pollen concentrations lead
to a weaker immune response in airways to viruses that can cause coughs
and colds. When a virus enters the body, infected cells usually send
out messenger proteins. This is also the case with SARS-CoV- 2. These
proteins, known as antiviral interferons, signal nearby cells to escalate
their antiviral defenses to keep the invaders at bay. Additionally,
an appropriate inflammation response is activated to fight the viruses.

But if airborne pollen concentrations are high, and pollen grains
are inhaled with the virus particles, fewer antiviral interferons
are generated. The beneficial inflammatory response itself is also
affected. Therefore, on days with a high concentration of pollen, it
can lead to an increase in the number of respiratory illnesses. This
also holds true for Covid-19. Whether individuals are allergic to the
different pollen types is irrelevant.

"You cannot avoid exposure to airborne pollen," says Stefanie Gilles
who is also first author of the study. "People in high-risk groups
should, therefore, be informed that high levels of airborne pollen concentrations lead to an increased susceptibility to viral respiratory
tract infections." Athanasios Damialis emphasizes: "When studying
the spread of SARS-CoV-2, environmental factors such as pollen must
be taken into account. Increased awareness of these effects are an
important step in preventing and mitigating the impact of Covid- 19."
Particle filtering masks provide protection What can vulnerable people
do to protect themselves? Claudia Traidl-Hoffmann, last author and a
professor of environmental medicine, advises people at high- risk to
monitor pollen forecasts over the coming months. Claudia Traidl- Hoffmann states: "Wearing a particle filtering mask when pollen concentrations
are high can keep both the virus and pollen out of the airways." ========================================================================== Story Source: Materials provided by
Technical_University_of_Munich_(TUM). Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Athanasios Damialis, Stefanie Gilles, Mikhail Sofiev, Viktoria
Sofieva,
Franziska Kolek, Daniela Bayr, Maria P. Plaza, Vivien Leier-Wirtz,
Sigrid Kaschuba, Lewis H. Ziska, Leonard Bielory, La'szlo' Makra,
Maria del Mar Trigo, Claudia Traidl-Hoffmann. Higher airborne pollen
concentrations correlated with increased SARS-CoV-2 infection rates,
as evidenced from 31 countries across the globe. Proceedings of
the National Academy of Sciences, 2021; 118 (12): e2019034118 DOI:
10.1073/pnas.2019034118 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/03/210309100129.htm

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