Microbial Growth on Dust-Loaded Filtering Materials Used for the Protection of Respiratory Tract as a Factor Affecting Filtration Efficiency

Abstract

This work aims at understanding the effects of various dust-loading conditions and the type of nonwovens used in the construction of FFRs on the safe use of those protective devices in situations of exposure to biological agents. The survival of microorganisms (Escherichia coli, Candida albicans, and Aspergillus niger) in dust-loaded polypropylene nonwovens (melt-blown, spun-bonded, and needle-punched) was experimentally determined using microbiological quantitative method (AATCC TM 100-2004). Scanning electron microscope was used to assess biofilm formation on dust-loaded filtering nonwovens. The impact of the growth of microorganisms on filtration efficiency of nonwovens was analysed based on the measurements of penetration of sodium chloride particles (size range 7–270 nm). Results showed that tested microorganisms were able to survive on dust-loaded polypropylene filtering nonwovens. The survival rate of microorganisms and penetration of nanoparticles and submicron particles depended on the type of microorganism, as well as the type and the amount of dust, which indicates that both of those factors should be considered for FFR use recommendations.

Survival of Microorganisms on Nonwovens Used for the Construction of Filtering Facepiece Respirators

“…Translating the results of laboratory tests into the actual use, it should be stated that the more effective the FFRs are, the more microorganisms will accumulate inside them. Their growth can constitute a danger to the user [21,22,23]. Therefore, the use of standard FFRs throughout the working shift for protection against biological agents does not guarantee a sufficient protection of the user.…”

“…Therefore, despite numerous research and development studies aimed at conferring biocidal properties to filtering nonwovens [4,5,6,7,8,9,10,11,12,13,14,15], there are no FFRs on the market that guarantee restricted growth of microorganisms accumulated on the filtering material during use. At the same time, many studies [16,17,18,19,20,21,22,23] confirmed that during prolonged FFR use against bioaerosols, bacterial numbers may increase, and biofilms may form on the filtering nonwoven, which may become a potential threat for the user. Likewise, it was found that during influenza A (H1N1) pandemics, viruses and microorganisms survived on the filtering material of SRs used by the personnel for several hours to several days [24,25,26].…”

“…Moisture and mineral dust from work environments may promote microorganism growth within filtering nonwovens [21,22,23]. Based on breathing simulation, Majchrzycka et al confirmed that moisture from exhaled air, which accumulate within FFRs creates favourable conditions for microorganism growth [21].…”

Microbiological Air Quality and Drug Resistance in Airborne Bacteria Isolated from a Waste Sorting Plant Located in Poland―A Case Study

“…These genes are common among the bacterial populations in the human microbiome and are not likely to be eradicated, even in the absence of antibiotic selection [74]. Therefore, it is important to use personal protective equipment (respiratory protection masks, footwear, protective clothing, and gloves), effective and efficient ventilation, as well as limiting the employees' working time in these conditions [75]. Although, there is a lack of BAQ standards in Polish legislation, the key problem is keeping a high standard of air quality, and we hope that the results of this campaign may indicate the usefulness of periodic microbiological environmental monitoring to verify the quality of the air and to establish possible technologically achievable guide levels of contamination for a specific work environment.…”

Survival of Microorganisms on Filtering Respiratory Protective Devices Used at Agricultural Facilities

“…The AATCC 100-1998 “Antimicrobial Finishes of Textile Materials” quantitative method was used to assess microorganism survival on filtering nonwovens. Microbial inocula were prepared according to a previously described method [37]. The inoculation suspension density at the level of 1.9 × 10 6 CFU/mL for B. subtilis , 7.5 × 10 8 CFU/mL for E. coli , 8.7 × 10 9 CFU/mL for S. aureus , 1.0 × 10 8 CFU/mL for C. albicans and 3.8 × 10 6 CFU/mL for A. niger was determined using the culture method and Thom chamber.…”