Application of Biocides and Super-Absorbing Polymers to Enhance the Efficiency of Filtering Materials

A Review of the Fabrication Methods, Testing, and Performance of Face Masks

Improvement in the performance and compatibility of face masks has remained the focus of researchers in recent years, especially after the emergence of the COVID pandemic. Although a lot of progress in the design, tolerability, and comfort of the mask has been reported, there are certain limitations, requiring further improvement. The present review aims to highlight the filtration efficacy, comfort, and associated characteristic of various types of face masks and respirators as a function of their design and structure. In addition, the air pollutants, their adverse effects on health, certified respirators, and face masks are also discussed. The present review also provides an insight into different types of commercially available face masks in terms of their materials, filtration efficiency, and limitations. The role of emerging trends (such as nanotechnology and high-performance polymers) in the improvement and development of face masks and respirators is also discussed.

Coating with Hypertonic Saline Improves Virus Protection of Filtering Facepiece Manyfold-Benefit of Salt Impregnation in Times of Pandemic

Recently, as is evident with the COVID-19 pandemic, virus-containing aerosols can rapidly spread worldwide. As a consequence, filtering facepieces (FFP) are essential tools to protect against airborne viral particles. Incorrect donning and doffing of masks and a lack of hand-hygiene cause contagion by the wearers' own hands. This study aimed to prove that hypertonic saline effectively reduces the infectious viral load on treated masks. Therefore, a hypertonic salt solution´s protective effect on surgical masks was investigated, specifically analyzing the infectivity of aerosolized Alphacoronavirus 1 in pigs (Transmissible Gastroenteritis Virus (TGEV)). Uncoated and hypertonic salt pre-coated FFPs were sprayed with TGEV. After drying, a defined part of the mask was rinsed with the medium, and the eluent was used for the infection of a porcine testicular cell line. Additionally, airborne microorganisms´ long-term infectivity of sodium-chloride in phosphate-buffered saline comprising 5% saccharose was investigated. In the results from an initial Median Tissue Culture Infectious Dose, infection rate of TGEV was minimally reduced by untreated FFP. In contrast, this could be reduced by a factor of 10⁴ if FFPs were treated with hypertonic salt solutions. Airborne pathogens did not contaminate the growth medium if salt concentrations exceeded 5%. We conclude that hypertonic saline is a vital tool for anti-virus protection, exponentially improving the impact of FFPs.

Nanofiber-Based Face Masks and Respirators as COVID-19 Protection: A Review

Wearing face masks, use of respirators, social distancing, and practicing personal hygiene are all measures to prevent the spread of the coronavirus disease (COVID-19). This pandemic has revealed the deficiency of face masks and respirators across the world. Therefore, significant efforts are needed to develop air filtration and purification technologies, as well as innovative, alternative antibacterial and antiviral treatment methods. It has become urgent—in order for humankind to have a sustainable future—to provide a feasible solution to air pollution, particularly to capture fine inhalable particulate matter in the air. In this review, we present, concisely, the air pollutants and adverse health effects correlated with long- and short-term exposure to humans; we provide information about certified face masks and respirators, their compositions, filtration mechanisms, and the variations between surgical masks and N95 respirators, in order to alleviate confusion and misinformation. Then, we summarize the electrospun nanofiber-based filters and their unique properties to improve the filtration efficiency of face masks and respirators.

A comprehensive review on antimicrobial face masks: an emerging weapon in fighting pandemics

The world has witnessed several incidents of epidemics and pandemics since the beginning of human existence. The gruesome effects of microbial threats create considerable repercussions on the healthcare systems. The continually evolving nature of causative viruses due to mutation or re-assortment sometimes makes existing medicines and vaccines inactive. As a rapid response to such outbreaks, much emphasis has been placed on personal protective equipment (PPE), especially face mask, to prevent infectious diseases from airborne pathogens. Wearing face masks in public reduce disease transmission and creates a sense of community solidarity in collectively fighting the pandemic. However, excessive use of single-use polymer-based face masks can pose a significant challenge to the environment and is increasingly evident in the ongoing COVID-19 pandemic. On the contrary, face masks with inherent antimicrobial properties can help in real-time deactivation of microorganisms enabling multiple-use and reduces secondary infections. Given the advantages, several efforts are made incorporating natural and synthetic antimicrobial agents (AMA) to produce face mask with enhanced safety, and the literature about such efforts are summarised. The review also discusses the literature concerning the current and future market potential and environmental impacts of face masks. Among the AMA tested, metal and metal-oxide based materials are more popular and relatively matured technology. However, the repeated use of such a face mask may pose a danger to the user and environment due to leaching/detachment of nanoparticles. So careful consideration is required to select AMA and their incorporation methods to reduce their leaching and environmental impacts. Also, systematic studies are required to establish short-term and long-term benefits.