Microscopic analysis of the FFP2 mask used to protect the respiratory system against urban pollutions

Introduction
Disposable medical masks commonly used to protect against airborne pathogenic microorganisms have gained popularity during the SARS-CoV-2 pandemic. Until the Comirnaty vaccine was approved by the European Commission on 21 December 2020, the masks had been basically the only protection against the infection. The manufacturer guaranteeing a bacterial filtration efficiency (BFE) of 95% also states that the masks are intended for protection of the respiratory system against pollutants and dust.

Aim of the research
The aim of the article is to assess the suitability of the mask as a means of protecting the respiratory system against harmful dust during the periods of high PM2.5 air levels. Using the microscopic examination of individual mask layers the quantitative and qualitative composition of the material subjected to aeration in the zone affected by urban pollution was analysed.

Material and methods
The FFP2 mask commonly available on the market, manufactured in accordance with the EN 149:20001 + A1:2009 standard, was analysed. Observations and sample analysis was conducted by using the Energy Dispersive Spectroscopy (EDS) microanalyser in a Scanning Electron Microscopy System FEI Quanta 250 in the UJK University Environmental Testing Laboratory, Kielce.

Results and conclusions
The experiment confirmed the effectiveness of protection against pollution provided by the protective mask made of 5-layer polypropylene (PP) non-woven fabric with slim design intended to protect the respiratory system against pathogenic microorganisms transmitted by droplets. The microscopic imaging revealed diverse particles on the surface of individual face mask layers, including multi-element conglomerates; particles of soot, minerals and concentric spherules with predominating share of Fe, Cr, Al and Mg.