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Face masks have been an effective and indispensable personal protective measure against particulate matter pollutants and respiratory diseases, especially the novel Coronavirus disease recently. However, disposable surgical face masks suffer from low filtration efficiency for particles ranging from nano- to micro-size, and the limited service life of ~ 4 h. Here, a nano/micro fibrous hybrid air filter mask composing of electrospun nanofibrous network and poly(3,4-ethylenedioxythiophene:poly(styrenesulfonate) coated polypropylene (PP) is proposed. Furthermore, the resultant filter is supplied with tribo-charges by a freestanding sliding triboelectric nanogenerator. Through the enhanced synergistic effect of mechanical interception and electrostatic forces, the hybrid air filter demonstrates high filtration efficiency for particle size of 11.5 nm to 2.5 µm, with a 9.3–34.68% enhancement for particles of 0.3–2.5 µm compared to pristine PP, and 48-h stable filtration efficiency of 94% (0.3–0.4 µm) and 99% (1–2.5 µm) with a low pressure drop of ~110 Pa. In addition, sterilization ability of the tribo-charge enhanced air filter is demonstrated. This work provides a facile and cost-effective approach for state-of-the-art face masks toward high filtration performance of nano- to micro- particles with greatly extended service life. A tribo-charge enhanced hybrid air filter mask is developed for efficient nano- to micro- sized particulate matter capture, with a 9.3–34.68% filtration enhancement for particles of 0.3–2.5 µm compared to state-of-the-art air filter used in disposable mask. A greatly extended service life to 48 h of stable filtration efficiency of 94% for 0.3–0.4 µm and 99% for 1–2.5 µm at a low pressure drop of ~110 Pa is demonstrated. [Display omitted] • A tribo-charge enhanced hybrid nano/micro air filter mask is developed with PEDOT:PSS as a conductive charging layer. • Capture efficiency is enhanced for both nano- to micro- sized particles, with an enhancement of 9.3–34.68% for 0.3–2.5 µm. • Extended service life of 48 h is demonstrated for stable capture efficiency of 94% (0.3–0.4 µm) and 99% (1–2.5 µm). • Enhanced synergistic effect of mechanical interception and electrostatic forces is proposed. • 100% sterilization ability of the tribo-charge enhanced air filter is demonstrated. [ABSTRACT FROM AUTHOR]

Infectious disease-causing pathogens can be transmitted via contact with contaminated environmental surfaces (i.e., fomite transmission). However, the physical mechanism of fomite transmission remains unclear because of a lack of suitable surrogate tracers. In this study, the non-toxic, non-human-origin and gram-positive bacterium Lactobacillus delbrueckii subsp. Bulgaricus was selected as a tracer, and its applicability for studying bacterial contamination spread on environmental surfaces was investigated in an office setting. After bacterial introduction by a designated carrier, surface contamination levels indicated by the L. bulgaricus proline iminopeptidase (pepIP) gene copy numbers were quantified using an optimized qPCR assay. This qPCR assay exhibited a high sensitivity (55 copies per reaction mixture and 1585 copies per surface sample), a wide dynamic range (7 orders of magnitude) and a high specificity for pepIP gene in environmental surface samples. Three independent, natural and unsupervised field experiments involving human participants confirmed the applicability of L. bulgaricus as a tracer in field studies and the pepIP gene as a unique marker of externally introduced contamination. Experimentally, contamination was distributed nearly equally over public surfaces, the carrier's seat location and the other seat locations in the office setting. An analysis by seat location revealed that the contamination level was attenuated as the physical distance from the carrier's seat location increased. Volunteers' faces were ubiquitously contaminated, suggesting a potentially high risk of fomite exposure via mucous membranes. In conclusion, L. bulgaricus can feasibly be used as a tracer organism in future large-scale field studies of bacterial contamination spread on environmental surfaces. [Display omitted] • The L. bulgaricus pepIP gene can be used as a tracer to study fomite transmission. • An optimized qPCR assay was developed to quantify the pepIP gene. • The qPCR assay was capable of handling complex environmental samples. • Surface contamination from the source was attenuated based on physical distance. • Volunteers' faces were ubiquitously contaminated by touch in field studies. [ABSTRACT FROM AUTHOR]