Posted: Saturday, November 21, 2020 1:02 PM
Although there are still those who deny it, the entire planet is still immersed in the serious health crisis caused by the coronavirus epidemic. For this reason, and until the establishment of an effective vaccine that can end COVID-19, it is necessary to continue to adhere to protective and safety measures, such as wearing masks, frequent washing. of the hands and the respect of a minimum distance from other people 1.5 or 2 meters.
To these measures, the multiple investigations which are trying to find the key to controlling the pandemic have also added other recommendations concerning the ventilation of confined spaces and the filtration of particles which are in the air and which carry the coronavirus. To further avoid the risks, it is necessary to take into account another tool, especially in the face of winter, which is difficult due to the spread of the virus.
Pay special attention to humidity. This was stated by three renowned scientists in a joint publication published in the Washington Post: Joseph G. Allen, professor and director of the “Healthy Buildings” program at the TH Chan School of Public Health at Harvard University; Akiko Iwasaki, professor of immunobiology at the Yale School of Medicine, and Linsey C. Marr, professor of civil and environmental engineering at Virginia Tech.
In their article, Allen, Iwasaki and Marr stress the importance of maintaining an environmental relative humidity of 40% to 60% in confined spaces. “Relative humidity is the term for the amount of water vapor that is actually in the air versus how much it can hold,” they explained in the column, where they explored this question with an example: “As it goes from fall to winter and we start to heat the air, our indoor environments become drier, often reaching 20% relative humidity, well below the ideal 40-60%.
Thus, they explain how “humidity can affect transmission: in dry air there is less mucus and the eyelashes do not beat as fast or in the right direction. This means less viral particles are captured or cleared from the airways, allowing many to reach the deepest part of our lungs, where they do the most damage. “In addition, they highlight a new study which claims that the coronavirus” breaks down faster at relative humidity close to 60% than at other levels. “
Finally, they remember that dry air also influences the distance that droplets containing the virus can travel and the time they can stay in the air: “When we speak, sing or breathe, we emit respiratory droplets. . Some are quite big and they quickly fall to the ground. But microscopics, which we call aerosols, stay in the air for hours and travel well beyond two meters. “
This is where, they say, “the problem lies: the lower the relative humidity, the faster these large droplets evaporate.” In this way, they emphasize that a relative humidity range of between 40% and 60% “is just at the optimum point where you get the advantages of having a little humidity, but not the disadvantages of too much” . Why is it so important to keep this in mind for the winter? Allen, Iwasaki, and Marr explain that in winter, “we’re going to be spending a lot more time indoors, where most of the transmission is happening.”
“In winter, we bring air inside and heat it. We increase the size of the sponge without adding more water vapor. Therefore, indoor relative humidity ends up being lower than outdoor. . ” Scientists recommend using portable humidifiers while claiming to defend “our homes, schools and offices” using the tools we currently have to deal with the pandemic until we have a vaccine in our hands that allows us to say goodbye to the coronavirus “.