Exposure to pollen can increase your risk of developing COVID-19, and it’s not just a problem for people with allergies, according to new research released on March 9th.
Plant physiologist Lewis Ziska, co-author of the new peer-reviewed study and other recent research on pollen and climate change, explains the findings and why pollen times are getting longer and more intense.
What does pollen have to do with a virus?
The most important takeaway from our new study is that pollen may be a factor in the exacerbation of COVID-19.
A few years ago, my co-authors showed that pollen can suppress the way the human immune system responds to viruses. By interfering with proteins that indicate antiviral reactions in cells in the airways, it can make people more susceptible to a number of respiratory viruses, such as the flu virus and other SARS viruses.
In this study, we looked specifically at COVID-19. We wanted to see how the number of new infections changed with the rise and fall of pollen levels in 31 countries around the world. We found that approximately 44 percent of the variability in COVID-19 cases is on average related to exposure to pollen, often in synergy with humidity and temperature.
Infection rates tend to rise four days after a high pollen count. If there was no local exclusion, the infection rate increased on average by about 4 percent per 100 pollen grains in a cubic meter of air. A strict closure reduced the increase by half.
This exposure to pollen is not just a problem for people with hay fever. This is a reaction to pollen in general. Even types of pollen that do not usually cause allergic reactions were correlated with an increase in COVID-19 infections.
What precautions can people take?
Try to stay indoors on days with lots of pollen to limit your exposure as much as possible.
If you are outdoors, wear a mask during the pollen season. Pollen grains are large enough that almost any mask designed for allergies will help keep them out. However, if you sneeze and cough, wear a mask that is effective against the coronavirus.
If you are asymptomatic with COVID-19, all sneezing increases your chances of spreading the virus. Mild cases of COVID-19 can also be mistaken for allergies.
Why does the pollen season last longer?
As the climate changes, we see three things specifically related to pollen.
The one is an earlier start of the pollen season. Spring changes start earlier, and there are worldwide signs of exposure to pollen earlier in the season.
Second, the overall pollen season is getting longer. The time you are exposed to pollen, from spring, which is mainly driven by tree pollen, to summer, which is weeds and grasses, and then autumn, which is mainly ragweed, is about 20 days longer in North America as it was in 1990.
As you move to the poles, where temperatures are rising faster, we have found that the season is getting even more pronounced.
Third, more pollen is produced. Colleagues and I all three described the changes in a paper published in February.
As climate change drives pollen counts upwards, it can lead to greater human susceptibility to viruses.
These changes in the pollen season have been going on for several decades. When my colleagues and I looked back at so many different records of pollen that we had been able to locate since the 1970s, we found good evidence to suggest that these shifts occurred at least over the past 30 to 40 years.
The concentrations of greenhouse gases are rising and the surface of the earth is getting warmer, and this is going to affect life as we know it. I have been studying climate change for 30 years. It is so endemic to the current environment that it will be difficult to look into any medical issue without at least trying to understand whether climate change has already affected or is going to do so.
Lewis Ziska, Associate Professor of Environmental Health Sciences, University of Columbia.
This article was published from The Conversation under a Creative Commons license. Read the original article.