HELSINKI – Face masks made of fabric only give 20-40% protection

While proper respirators made of polyester can remove some 90% of the droplets in the air, the level of protection afforded by fabric face masks lies somewhere between 20% and 40%, according to a new study published on Thursday (14 May) by the VTT Technical Research Centre of Finland.

The fabric masks do, however, play a significant role in reducing the spread of the virus.

When a person is coughing – and possibly carrying a virus – droplets spread within a radius of up to a few metres. A fabric mask shortens the distance down to less than half a metre.

The VTT research also underlines the importance of changing a fabric mask to a clean one after an hour’s use, preferably even after 30 minutes, as well as the need to wash them efficiently. 

“My personal point of view is that wearing face masks should not be compulsory. In Finland, there are roughly one million people for whom there could be a risk by worsening their breathing problems. But, for others wearing them is recommendable,” VTT Research Professor Said Ali Harlin told tabloid Ilta-Sanomat.

(Pekka Vänttinen |

Subscribe to our newsletters