Measuring breathability and bacterial filtration efficiency of face masks in the pandemic context: A round robin study with proficiency testing among non-accredited laboratories

Tessarolo, Francesco;Nollo, Giandomenico;Benedetti, Luca;Helfer, Fabrizia;Rovati, Luigi;Ferrari, Alberto;Marchetti, Giulio;Reverberi, Federico;Baglio, Salvo;Tuccitto, Nunzio;Stefani, Stefania;Stracquadanio, Stefano;Caraci, Filippo;Terrasi, Antonio;Tricomi, Alessia;Musumeci, Mario;Miraglia, Andrea;Cuttone, Giacomo;Cosentino, Sofia;Agostino Vitali, Luca;Petrelli, Dezemona;Ilaria Ciancia, Sonia;Mingoia, Marina;Castellini, Paolo;Simoni, Serena;Montalto, Luigi;Baleani, Alessia;Chiariotti, Paolo;Paone, Nicola

2022-01-01

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Abstract

Six Italian non-accredited laboratories participated to an interlaboratory study aimed at measuring Differential Pressure (DP) and Bacterial Filtration Efficiency (BFE) of three face-mask models using methods in-line with EN 14683 standard. Methodological non-conformities were annotated. Repeatability and reproducibility on quintuplicate samples were calculated according to ISO 5725-2. Sample stability was also assessed. Laboratories were ranked according to the total standard deviation over all samples and proficiency was evaluated using z-score according to ISO 13528. Although some non-conformities were present, performances for the DP measurements were always acceptable. One laboratory had to revise the bacterial suspension preparation for the BFE test. Overall, non-accredited laboratories working during pandemic emergency performed satisfactorily. Sample-to-sample variability impacted measurement repeatability. BFE values above 98% showed good repeatability (≤1.0%) and reproducibility (≤6.1%), but high BFE uncertainty was associated to community masks. Our findings suggest that relevant face-mask conformity standards should consider uncertainty of BFE and DP measurements.