How Effective Is the Filtration of 'KN95' Filtering Facepiece Respirators During the COVID-19 Pandemic?

The face behind the Covid-19 mask - A comprehensive review

The threat of epidemic outbreaks like SARS-CoV-2 is growing owing to the exponential growth of the global population and the continual increase in human mobility. Personal protection against viral infections was enforced using ambient air filters, face masks, and other respiratory protective equipment. Available facemasks feature considerable variation in efficacy, materials usage and characteristic properties. Despite their widespread use and importance, face masks pose major potential threats due to the uncontrolled manufacture and disposal techniques. Improper solid waste management enables viral propagation and increases the volume of associated biomedical waste at an alarming rate. Polymers used in single-use face masks include a spectrum of chemical constituents: plasticisers and flame retardants leading to health-related issues over time. Despite ample research in this field, the efficacy of personal protective equipment and its impact post-disposal is yet to be explored satisfactorily. The following review assimilates information on the different forms of personal protective equipment currently in use. Proper waste management techniques pertaining to such special wastes have also been discussed. The study features a holistic overview of innovations made in face masks and their corresponding impact on human health and environment. Strategies with SDG3 and SDG12, outlining safe and proper disposal of solid waste, have also been discussed. Furthermore, employing the CFD paradigm, a 3D model of a face mask was created based on fluid flow during breathing techniques. Lastly, the review concludes with possible future advancements and promising research avenues in personal protective equipment.

Assessment of best-selling respirators and masks: Do we have acceptable respiratory protection for the next pandemic?

Background

COVID-19 pandemic caused a high demand for respiratory protection, caused a scarcity of approved respirators and the production of alternative respiratory protection. To raise public awareness through the scientific community, bestselling respirators and masks in the United States’ leading online retailer, Amazon.com, were evaluated.

Methods

Ten respirators and masks, 5 Face Protective Equipment (FPE) and 5 Cloth Face Masks (CFMs), were evaluated compared to the N95 standard. Two groups were established with the intention of comparing all masks together. The fractional efficiency and pressure drop were measured and compared to the National Institute for Occupational Safety and Health (NIOSH) standards. In addition, grading factors for protection, comfort, and affordability were developed that can be used by the scientific community to readily disseminate to consumers for the selection of the appropriate respiratory protection.

Results

Two FPE provided acceptable efficiency (>95%) similar to the N95, while the remaining products were below or extremely below NIOSH standards. All products provided pressure drops within NIOSH standards (≤35 mmH₂O) ranging from 2.3-10.3 mmH₂O. The grading factors show that the CFMs have minimal protection, and the N95 has average comfort and affordability compared to all the products.

Conclusion

The N95 remains the best respiratory protection, and in the event of the next airborne pandemic, FPEs could serve as adequate alternative protection against the viral spread.

Performance Evaluation of Commercially Available Masks in Korea for Filtering Airborne Droplets Containing Bacteria

The coronavirus disease (COVID-19) pandemic is a global health threat and has posed a challenge for society and social care services as well as healthcare systems. Due to the risks involved in being exposed to the virus, public health actions such as wearing masks and physical distancing are necessary to reduce its spread. However, using non-validated masks is a serious issue as such masks may provide inadequate protection against airborne bioaerosol transmission, resulting in the spread of the virus. Therefore, it is necessary to evaluate the filtering performances of the masks against bioaerosols as well as particulate matter (PM). Here, we evaluated the filtering performances of sixteen different masks (four brands each of woven, antidroplet, KF80, and KF94 masks) commercially available in Korea with high market shares. As a simulation of being exposed to bioaerosols and to the yellow dust commonly found in Korea, the filtration efficiency levels of the masks were tested against airborne bacteria-containing droplets and against fine dusts of different ranges of particle sizes. Their filtration efficiency levels against the droplets showed strong positive correlations, specifically Pearson correlation coefficient r values of 0.917, 0.905, and 0.894, with their efficiency levels against PM1.0, PM2.5, and PM10, respectively. The results of this study should be useful for choosing appropriate masks, including those that meet filtering performance requirements.

Examination of Nanoparticle Filtration by Filtering Facepiece Respirators During the COVID-19 Pandemic

The onset of the COVID-19 pandemic in spring 2020 resulted in a spike in the demand for face masks and respirators. Due to their effectiveness at filtering aerosols that could potentially contain viruses, the N95-type filtering facepiece respirators (FFRs) are frequently used by healthcare workers and first responders. However, due to a shortage of domestic N95 FFRs in the US at the beginning of the pandemic, internationally produced respirators were imported and deployed under an Emergency Use Authorization by the Food and Drug Administration. Due to concerns raised at the time, there was an urgent need to verify their effectiveness and usability. In this study, we summarize our characterization of the nanoparticulate filtration performances of 136 such respirators, measured between April 1 and June 30, 2020. Our results indicate that about 42% of the respirators showed filtration efficiencies better than 90% (≤10% penetration), but only 17% performed better than 95% (≤5% penetration). On the other hand, about 35% showed filtration efficiencies below 80% (≥20% penetration). A representative subset of devices was analyzed for the origin of such variations in filtration performance. We found that filtration efficiency increased with the level of electrostatic charge on the FFRs and that the poor performance of the internationally sourced FFRs could be traced to a lack of electrostatic filtration mechanisms. Furthermore, electrostatics shifted the particle size at which aerosol penetration through the FFR was maximal from around 200 nm to less than 100 nm for the highest-performing FFRs, a size range that largely goes undetected in standardized tests.