Research into face mask leakage
Philomena Bluyssen and Marco Ortiz are developing a method in the SenseLab to compare leakage rates in different non-medical face masks. Up to now the NEN standard does not contain such a test.
The Dutch standardisation institute NEN (Stichting Koninklijk Nederlands Normalisatie Instituut) recently published a standard for face masks for public use (version 9-11-2020) which includes requirements for design, use and maintenance. The tests named in the standard are: visual inspection, strength test, filtration-efficiency test, and breath-resistance test. As yet there is no test indicated for external leakage around the edges of the mask.
Bluyssen and her colleagues are working in the SenseLab to develop a leakage test, using a test set-up comprising a plastic head with an atomiser that emits various sized droplets via the nose. The set-up simulates aerosol secretion during breathing: the droplets are rendered visible in UV light through the addition of a yellow marker.
The first tests of non-medical face masks, in collaboration with the Dutch television programme Kassa, show that many masks ‘leak’ around the nose, cheeks and chin due to their poor fit. And sometimes the material allows water droplets to pass through it.
Bluyssen and her colleagues are continuing these tests, and an official publication will follow.
Update - July 2021
The results of this research are published in the journal Intelligent Buildings International, in July 2021. Read the article here.