Elsevier‘s Q1 ranked journal, "Measurement", the journal of IMEKO (Internationla Measurement Confederation) published the article written by Balázs Illés PhD and Péter Gordon PhD.

Their paper "Filtering efficiency measurement of respirators by laser-based particle counting method" presents a novel method for measuring and evaluating the filetering material of respirators, one of the most important personal protective equipment in the COVID pandemic.

An easy and fast filtering efficiency measurement method was developed. It works with a laser-based particle counting method, and it can determine two types of filtering efficiencies: Particle Filtering Efficiency (PFE) at given particle sizes and Concentration Filtering Efficiency (CFE) in the case of different aerosols. The measurement method was validated with different aerosol concentrations and with etalon respirators.

Considerable advantages of their measurement method are simplicity, availability, and the relatively low price compared to the flame-photometer based methods.

The ability of the measurement method was tested on ten different types of Chinese KN95 respirators. The quality of these respirators differs much, only two from ten reached 95% filtering efficiency.

The research was partially financed by the National Research, Development and Innovation Office in Hungary, NRDI fund, project code 2020-2.1.1-ED-2020-00019.

The full article is open-access and available by clicking on the image: