As the coronavirus spreads mainly through air as a droplet infection, wearing a mask is important in limiting its spread, but it is even more important to ensure adequate air ventilation, Heikki Junninen, a researcher at the University of Tartu, said.
"The most important thing is to know that the virus spreads through the air. Therefore, it would still be necessary to wear a mask to prevent infection," Junninen said.
He stressed that this was particularly relevant to the delta strain, which is even more contagious than previous coronavirus variants.
However, wearing a mask is not a panacea; it works together with other measures, Junninen said. "Wearing a mask alone is not useful."
He said that it is even more important to ensure fresh air, to prevent the virus from spreading - so that people do not have to breathe in the air already exhaled by others. "Good indoor air quality must be ensured by good ventilation. In warm weather, this is easy to achieve - the windows must be opened. But in cold weather, ventilation is important and therefore masks are important," the professor.
He said that it is worth monitoring the CO2 indicator at a given premises. If the indicator reads less than 1,000 units, the situation is safe.
In relation to the masks' effectiveness, Junninen said that the virus can get "trapped" by a mask that is opaque, meaning there is little difference between wearing a disposable mask or a reusable one.
However, to disinfect the mask, it is sufficient to leave it in freshly boiled water for five minutes.
When asked how he assesses the mask requirement, which will take effect on Thursday, Junninen said that it is safer to wear a mask because we do not know how good the ventilation in the room is.
At the same time, the need to give a mask also depends on the number of people in the room. "Indoor air quality is still important, but if it is not guaranteed, it is important to wear a mask," the professor said.
Commenting on the need to wear a mask outdoors, Junninen found this to be generally not necessary, perhaps only at large public events, where an individual might pass on a droplet infection to another person nearby.
The new restrictions will be in place from Thursday, August 26. Read them here.
Editor: Roberta Vaino