Based on new global research, there is a link between the incidence of coronavirus infections and high pollen counts in the air.
The study found that high pollen counts, partially affected by air humidity and temperature, contributed to a more than 40 percent increase in coronavirus infection frequency.
Exposure to pollen weakens the immune system's defence reactions against certain seasonal viruses.
This means that exposure to pollen can impair the body's ability to fight viruses, according to the University of Turku and the Finnish Meteorological Institute (FMI), which issued a joint statement about the study's findings on Tuesday.
The organisations noted that Finland's pollen season is about to begin and that people should limit their exposure to it.
"It's important to pay particular attention to times when pollen concentrations are high. Exposure to pollen should be reduced, for example, by avoiding outdoor activities when pollen concentrations are high or by protecting the respiratory tract," said Mikhail Sofiev, an FMI research professor who participated in the analysis of the research data.
In most cases, infection frequency increased four days after the peak pollen concentration, which roughly corresponds to the incubation period of the coronavirus.
However, the phenomenon is not linked to pollen allergies. Several other factors affect coronavirus infection frequency, according to the statement.
The international study also assessed the impact of the various restrictive measures taken to contain the spread of the virus in spring 2020.
"Restrictive measures halved the frequency of infections, compared to situations where no measures were taken, despite high levels of pollen in the air. During periods of restrictions, people are likely to be less exposed to both the virus and pollen that weakens the immune system. In the absence of restrictive measures, high concentrations of pollen can increase the frequency of infections significantly," the joint statement said.
Over 150 researchers participated in the study, and the research material was compiled from 31 countries.