[Analysis of Flame Retardants Bis(2,3-dibromopropyl) phosphate and Tris(2,3-dibromopropyl) phosphate in Textile Products by GC-MS].

The use of flame retardants, namely bis(2,3-dibromopropyl) phosphate (BDBPP) and tris(2,3-dibromopropyl) phosphate (TDBPP), in textile products such as curtains, carpets and sleeping clothes is banned in Japan under the 'Act on the Control of Household Products Containing Harmful Substances'. Herein, we developed a GC-MS based method to quantify these compounds with greater accuracy and safety than the current official method. For accurate and sensitive quantification, deuterated compounds, BDBPP-d10 and TDBPP-d15, were used as surrogate standards. In consideration of the safety of the analyst, certain solvents and reagents used for the pretreatment that are carcinogenic or have a risk of explosion were replaced. For the extraction step, benzene was replaced by ethyl acetate, and for the methyl derivatization step, the reagent was changed from a self-prepared solution of diazomethane in ether to a solution of trimethylsilyl diazomethane in hexane, a safe and easy-to-use commercially available reagent. The calibration curves were liner in the range of 0.5-8.0 µg/mL for both methylated BDBPP (BDBPP-Me) and TDBPP. The detection limit was 0.05 µg/g for BDBPP-Me and 0.3 µg/g for TDBPP, which is sufficiently low compared to the current detection limits of 10 µg/g for BDBPP-Me and 8 µg/g for TDBPP. The recoveries in various curtain material were 66-108% and relative standard deviations were 1.2-10.2% when 5 µg BDBPP and TDBPP were added to 0.5 g of samples. Thus, the developed method is applicable to textile products of various materials.

Reconciling human health with the environment while struggling against the COVID-19 pandemic through improved face mask eco-design.

Surgical masks have become critical for protecting human health against the COVID-19 pandemic, even though their environmental burden is a matter of ongoing debate. This study aimed at shedding light on the environmental impacts of single-use (i.e., MD-Type I) versus reusable (i.e., MD-Type IIR) face masks via a comparative life cycle assessment with a cradle-to-grave system boundary. We adopted a two-level analysis using the ReCiPe (H) method, considering both midpoint and endpoint categories. The results showed that reusable face masks created fewer impacts for most midpoint categories. At the endpoint level, reusable face masks were superior to single-use masks, producing scores of 16.16 and 84.20 MPt, respectively. The main environmental impacts of single-use masks were linked to raw material consumption, energy requirements and waste disposal, while the use phase and raw material consumption made the most significant contribution for reusable type. However, our results showed that lower environmental impacts of reusable face masks strongly depend on the use phase since reusable face masks lost their superior performance when the hand wash scenario was tested. Improvement of mask eco-design emerged as another key factor such as using more sustainable raw materials and designing better waste disposal scenarios could significantly lower the environmental impacts.

Assessment of Natural Sunlight Protection Provided by 10 High-SPF Broad-Spectrum Sunscreens and Sun-Protective Fabrics.

In 1978, the FDA Advisory Panel proposed both indoor and natural sunlight SPF testing methods but reverted to indoor testing only in 1993. Today's sunscreen sun protection and broad-spectrum claims are based on mandated clinical tests using solar simulators and in vitro spectrophotometers. This research evaluated the protection of 10 high-SPF (30-110), broad-spectrum sunscreen products, as well as 6 sun-protective fabrics against natural sunlight in Arequipa, Peru. Each of the 17 subjects was exposed to natural sunlight for 1 h and 59 min under clear skies, with temperatures and humidity similar to those in an indoor clinical laboratory. Test sites were photographed 16-24 h later. Four dermatologists evaluated the photographs for erythema and persistent pigment darkening (PPD). Perceptible sun-induced skin injury (sunburn and/or pigmentation) was detected at 97% of the sunscreen-protected scores. The most sun-sensitive subjects obtained the least erythema protection. The higher the SPF was, the higher the erythema protection, but the intensity of PPD was also higher. The 2 sunscreens using only FDA-approved sunscreen filters rated 30 SPF and 45+ SPF performed poorly: Eighty-one percent of the 136 scores were graded 1 minimal erythema dose or higher erythema, achieving, at a maximum, SPF of 5-7 in natural sunlight. Sun-protective fabrics tested provided excellent sun protection. The erythema and PPD observed through the sunscreens in less than 2 h are incongruous with the broad-spectrum, high-SPF sunscreen claims. Reapplying these sunscreens and staying in the sun longer, as stated on the product labels, would have subjected the subjects to even more UV exposure. High-SPF, broad-spectrum sunscreen claims based on indoor solar simulator testing do not agree with the natural sunlight protection test results.

Preparation, characterization, and application of polysaccharide-based emulsions incorporated with lavender essential oil for skin-friendly cellulosic support.

This study aimed to develop polysaccharide-based emulsions incorporated with lavender essential oil and their application on cellulosic support for patches obtaining. The lavender essential oil has been added to emulsions as an active compound mainly due to its antimicrobial properties. In this study, emulsions were used to deliver active ingredients (lavender essential oil). The chemical composition of essential oil was analyzed using gas chromatography-mass spectrometry (GC/MS). A total of seven emulsions (RiACL) were evaluated by determining rheological parameters and microbiological analysis. One of the emulsions (R7ACL) was applied to cellulosic support to obtain non-irritating textiles with controlled release of the active compound and moisturizing effects. Obtained cellulosic support was analyzed in terms of active compound controlled release, toxicity and antimicrobial testing, and skin analysis in healthy volunteers. It was found that the cellulosic supports treated with O/W emulsions are non-irritating, have softness and moisturizing effects, and can be used safely in topical applications for patches obtaining.

[Examination of Analytical Method for Mothproofing Agents to Revise the Official Methods Based on "Act on the Control of Household Products Containing Harmful Substances"].

In Japan, the use of mothproofing agents [dieldrin and 4,6-dichloro-7-(2,4,5-trichlorophenoxy)-2-trifluoromethylbenzimidazole; DTTB] in textiles is regulated by the Act on the Control of Household Products Containing Harmful Substances. Since official analytical methods for these agents have been in place for approximately 40 years, we developed an improved method in a previous study. In the present study, we validated this method. Accordingly, six laboratories analyzed the sample prepared at 3 µg/g (1/10 of the regulation value) and 30 µg/g (the regulation value). The high accuracy of the results for these samples in almost all the cases (accuracy: 70-120%, repeatability: <10%, reproducibility: <15%), confirmed the validity of the method. In addition, we examined three samples that were distributed before the introduction of the regulation. The analysis results for these samples showed little variation between laboratiories, indicating that our method is also applicable to actual samples. Meanwhile, the quantitative value was clearly lower in one laboratory than in the others. We presumed that the enhanced effect of the sample matrix (matrix effect) on the internal standards in GC-MS analysis was the main cause for this trend. Therefore, we examined the analytical method using polyethylene glycol 300 (PEG) as an analyte protectant. As PEG minimized the GC-MS response difference between the standard solution and the matrix-containing solution, GC-MS analysis with PEG would be useful for matrix effect measurements in this method.

One size fits all?: A simulation framework for face-mask fit on population-based faces.

The use of face masks by the general population during viral outbreaks such as the COVID-19 pandemic, although at times controversial, has been effective in slowing down the spread of the virus. The extent to which face masks mitigate the transmission is highly dependent on how well the mask fits each individual. The fit of simple cloth masks on the face, as well as the resulting perimeter leakage and face mask efficacy, are expected to be highly dependent on the type of mask and facial topology. However, this effect has, to date, not been adequately examined and quantified. Here, we propose a framework to study the efficacy of different mask designs based on a quasi-static mechanical model of the deployment of face masks onto a wide range of faces. To illustrate the capabilities of the proposed framework, we explore a simple rectangular cloth mask on a large virtual population of subjects generated from a 3D morphable face model. The effect of weight, age, gender, and height on the mask fit is studied. The Centers for Disease Control and Prevention (CDC) recommended homemade cloth mask design was used as a basis for comparison and was found not to be the most effective design for all subjects. We highlight the importance of designing masks accounting for the widely varying population of faces. Metrics based on aerodynamic principles were used to determine that thin, feminine, and young faces were shown to benefit from mask sizes smaller than that recommended by the CDC. Besides mask size, side-edge tuck-in, or pleating, of the masks as a design parameter was also studied and found to have the potential to cause a larger localized gap opening.

Moisture-Wicking and Solar-Heated Coaxial Fibers with a Bark-like Appearance for Fabric Comfort Management.

Maintaining the human body's comfort is a predominant requirement of functional textiles, but there are still considerable drawbacks to design an intelligent textile with proper moisture absorption and evaporation properties. Herein, we develop moisture-wicking and solar-heated coaxial fibers with a bark-like appearance for fabric comfort management. The cortex layer of coaxial fibers can absorb moisture via the synergistic effect of the hierarchical roughness and the hydrophilic polymeric matrix. The core layer containing zirconium carbide nanoparticles can assimilate energy from the body and sunlight, which raises the surface temperature of the material and accelerates moisture evaporation. The resulting coaxial fiber-based membrane exhibits an excellent droplet diffusion radius of 2.73 cm, an excellent wicking height of 6.97 cm, and a high surface temperature of 61.7 °C which is radiated by simulated sunlight. Moreover, the designed fabric also exhibits a significant UV protection factor of 2000. Overall, the successful synthesis of such fascinating fibrous membranes enables the rapid removal of sweat from the human body textile, providing a suitable and comfortable microenvironment for the human body.

Forgotten Technology in the COVID-19 Pandemic: Filtration Properties of Cloth and Cloth Masks-A Narrative Review.

Management of the global crisis of the coronavirus disease 2019 pandemic requires detailed appraisal of evidence to support clear, actionable, and consistent public health messaging. The use of cloth masks for general public use is being debated, and is in flux. We searched the MEDLINE and EMBASE databases and Google for articles reporting the filtration properties of flat cloth or cloth masks. We reviewed the reference lists of relevant articles to identify further articles and identified articles through social and conventional news media. We found 25 articles. Study of protection for the wearer used healthy volunteers, or used a manikin wearing a mask, with airflow to simulate different breathing rates. Studies of protection of the environment, also known as source control, used convenience samples of healthy volunteers. The design and execution of the studies was generally rigorously described. Many descriptions of cloth lacked the detail required for reproducibility; no study provided all the expected details of material, thread count, weave, and weight. Some of the homemade mask designs were reproducible. Successful masks were made of muslin at 100 threads per inch (TPI) in 3 to 4 layers (4-layer muslin or a muslin-flannel-muslin sandwich), tea towels (also known as dish towels), made using 1 layer (2 layers would be expected to be better), and good-quality cotton T-shirts in 2 layers (with a stitched edge to prevent stretching). In flat-cloth experiments, linen tea towels, 600-TPI cotton in 2 layers, and 600-TPI cotton with 90-TPI flannel performed well but 80-TPI cotton in 2 layers did not. We therefore recommend cotton or flannel at least 100 TPI, at least 2 layers. More layers, 3 or 4, will provide increased filtration but there is a trade-off in that more layers increases the resistance to breathing. Although this is not a systematic review, we included all the articles that we identified in an unbiased way. We did not include gray literature or preprints. A plain language summary of these data and recommendations, as well as information on making, wearing and cleaning cloth masks is available at www.clothmasks.ca.

Selection of homemade mask materials for preventing transmission of COVID-19: A laboratory study.

The Coronavirus Disease 2019 (COVID-19) has swept the whole world with high mortality. Since droplet transmission is the main route of transmission, wearing a mask serves as a crucial preventive measure. However, the virus has spread quite quickly, causing severe mask shortage. Finding alternative materials for homemade masks while ensuring the significant performance indicators will help alleviate the shortage of masks. Referring to the national standard for the "Surgical Mask" of China, 17 materials to be selected for homemade masks were tested in four key indicators: pressure difference, particle filtration efficiency, bacterial filtration efficiency and resistance to surface wetting. Eleven single-layer materials met the standard of pressure difference (≤49 Pa), of which 3 met the standard of resistance to surface wetting (≥3), 1 met the standard of particle filtration efficiency (≥30%), but none met the standard of bacterial filtration efficiency (≥95%). Based on the testing results of single-layer materials, fifteen combinations of paired materials were tested. The results showed that three double-layer materials including double-layer medical non-woven fabric, medical non-woven fabric plus non-woven shopping bag, and medical non-woven fabric plus granular tea towel could meet all the standards of pressure difference, particle filtration efficiency, and resistance to surface wetting, and were close to the standard of the bacterial filtration efficiency. In conclusion, if resources are severely lacking and medical masks cannot be obtained, homemade masks using available materials, based on the results of this study, can minimize the chance of infection to the maximum extent.

Particle removal from air by face masks made from Sterilization Wraps: Effectiveness and Reusability.

Wearing face masks is highly recommended to prevent SARS-CoV-2 transmission in health care workers and for the general public. The demand for high quality face masks has seen an upsurge in the recent times, leading to exploration of alternative economic and easily available options, without compromising on the quality. Particle removal from air in terms of capture efficiency of the filter media or the face mask is a crucial parameter for testing and quality assurance. Short-term reusability of the face masks is also an important aspect as the demand for masks will potentially outstrip the supply in future. Sterilization Wraps, which are used to wrap sterile surgical instruments, have shown a promising performance in terms of removal of particles from air. In this study, we evaluate the particle filtration characteristics of face masks made of 2 different metric weights [45 and 60 gram per square metre (GSM)] respectively, using locally available Sterilization Wraps. The aerosol filtration characteristics were also studied after sterilisation by different techniques such as heat with 50% humidity (thermal treatment), ethylene oxide (ETO), steam and radiation dose of 30kGy. We found that 60 GSM face mask had particle capture efficiency of 94% for total particles greater than 0.3 microns and this capture efficiency was maintained even after sterilisation with ETO and thermal treatment. The cost of producing these masks was 30 US cents/mask at our institute. Our study suggests that sterilization wrap material made of non-woven polypropylene spunbond-meltblown-spunbond (SMS) fibres could be an appropriate readily available inexpensive material for making face masks or N95 respirators.

Evaluation of Regeneration Processes for Filtering Facepiece Respirators in Terms of the Bacteria Inactivation Efficiency and Influences on Filtration Performance.

The regeneration of filtering facepiece respirators (FFRs) is of critical importance because of the severe shortage of FFRs during large-scale outbreaks of respiratory epidemics, such as COVID-19. Comprehensive experiments regarding FFR regeneration were performed in this study with model bacteria to illustrate the decontamination performance of the regeneration processes. The results showed that it is dangerous to use a contaminated FFR without any microbe inactivation treatment because the bacteria can live for more than 8 h. The filtration efficiency and surface electrostatic potential of 75% ethanol-treated FFRs were significantly reduced, and a most penetrating particle size of 200 nm was observed. Steam and microwave irradiation (MWI) showed promising decontamination performances, achieving 100% inactivation in 90 and 30 min, respectively. The filtration efficiencies of steam-treated FFRs for 50 and 100 nm particles decreased from 98.86% and 99.51% to 97.58% and 98.79%, respectively. Ultraviolet irradiation (UVI) effectively inactivated the surface bacteria with a short treatment of 5 min and did not affect the filtration performance. However, the UV dose reaching different layers of the FFP2 mask sample gradually decreased from the outermost layer to the innermost layer, while the model bacteria on the second and third layers could not be killed completely. UVI+MWI and steam were recommended to effectively decontaminate the used respirators and still maintain the respirators' filtration efficiency. The present work provides a comprehensive evaluation for FFR regeneration in terms of the filtration efficiencies for 50-500 nm particles, the electrostatic properties, mechanical properties, and decontamination effects.

A laboratory-based study examining the properties of silk fabric to evaluate its potential as a protective barrier for personal protective equipment and as a functional material for face coverings during the COVID-19 pandemic.

The worldwide shortage of single-use N95 respirators and surgical masks due to the COVID-19 pandemic has forced many health care personnel to use their existing equipment for as long as possible. In many cases, workers cover respirators with available masks in an attempt to extend their effectiveness against the virus. Due to low mask supplies, many people instead are using face coverings improvised from common fabrics. Our goal was to determine what fabrics would be most effective in both practices. Under laboratory conditions, we examined the hydrophobicity of fabrics (cotton, polyester, silk), as measured by their resistance to the penetration of small and aerosolized water droplets, an important transmission avenue for the virus causing COVID-19. We also examined the breathability of these fabrics and their ability to maintain hydrophobicity despite undergoing repeated cleaning. Laboratory-based tests were conducted when fabrics were fashioned as an overlaying barrier for respirators and when constructed as face coverings. When used as material in these two situations, silk was more effective at impeding the penetration and absorption of droplets due to its greater hydrophobicity relative to other tested fabrics. We found that silk face coverings repelled droplets in spray tests as well as disposable single-use surgical masks, and silk face coverings have the added advantage over masks such that they can be sterilized for immediate reuse. We show that silk is a hydrophobic barrier to droplets, can be more breathable than other fabrics that trap humidity, and are re-useable via cleaning. We suggest that silk can serve as an effective material for making hydrophobic barriers that protect respirators, and silk can now be tested under clinical conditions to verify its efficacy for this function. Although respirators are still the most appropriate form of protection, silk face coverings possess properties that make them capable of repelling droplets.

Cloth masks as respiratory protections in the COVID-19 pandemic period: evidence gaps.

OBJECTIVE: to identify scientific evidence on the effectiveness of using cloth masks as safe protectors against COVID-19. METHOD: an integrative review of articles available in full obtained at PubMed, CINAHL, and Web of Science. Controlled, non-controlled descriptors and keywords such as "mask", "home-made" and "cloth" or "cotton" and "infection control" or "infection prevention" were used. RESULTS: thirty-eight articles were selected; of these, seven studies made up the sample. Evidence shows that cloth masks do not have the same protective characteristics as surgical masks, indicating an increased risk of infection due to humidity, diffusion of fluids, virus retention, and improper preparation. Considering the shortage of surgical masks during the pandemic, cloth masks could be proposed as a last resort. CONCLUSION: cloth masks should be used together with preventive measures, such as home insulation, good respiratory conduct, and regular hand hygiene.

Decontamination of SARS-CoV-2 and Other RNA Viruses from N95 Level Meltblown Polypropylene Fabric Using Heat under Different Humidities.

In March of 2020, the World Health Organization declared a pandemic of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The pandemic led to a shortage of N95-grade filtering facepiece respirators (FFRs), especially surgical-grade N95 FFRs for protection of healthcare professionals against airborne transmission of SARS-CoV-2. We and others have previously reported promising decontamination methods that may be applied to the recycling and reuse of FFRs. In this study we tested disinfection of three viruses, including SARS-CoV-2, dried on a piece of meltblown fabric, the principal component responsible for filtering of fine particles in N95-level FFRs, under a range of temperatures (60-95 °C) at ambient or 100% relative humidity (RH) in conjunction with filtration efficiency testing. We found that heat treatments of 75 °C for 30 min or 85 °C for 20 min at 100% RH resulted in efficient decontamination from the fabric of SARS-CoV-2, human coronavirus NL63 (HCoV-NL63), and another enveloped RNA virus, chikungunya virus vaccine strain 181/25 (CHIKV-181/25), without lowering the meltblown fabric's filtration efficiency.

Sustainable Personal Protective Clothing for Healthcare Applications: A Review.

Personal protective equipment (PPE) is critical to protect healthcare workers (HCWs) from highly infectious diseases such as COVID-19. However, hospitals have been at risk of running out of the safe and effective PPE including personal protective clothing needed to treat patients with COVID-19, due to unprecedented global demand. In addition, there are only limited manufacturing facilities of such clothing available worldwide, due to a lack of available knowledge about relevant technologies, ineffective supply chains, and stringent regulatory requirements. Therefore, there remains a clear unmet need for coordinating the actions and efforts from scientists, engineers, manufacturers, suppliers, and regulatory bodies to develop and produce safe and effective protective clothing using the technologies that are locally available around the world. In this review, we discuss currently used PPE, their quality, and the associated regulatory standards. We survey the current state-of-the-art antimicrobial functional finishes on fabrics to protect the wearer against viruses and bacteria and provide an overview of protective medical fabric manufacturing techniques, their supply chains, and the environmental impacts of current single-use synthetic fiber-based protective clothing. Finally, we discuss future research directions, which include increasing efficiency, safety, and availability of personal protective clothing worldwide without conferring environmental problems.

Face masks. Technical, technological and functional characteristics and hygienic-sanitary aspects related to the use of filtering mask in the community.

INTRODUCTION: The health emergency caused by the spread of SARS-COV-2 virus has required the adoption of passive measures against contagion, such as social distancing. The use of filtering masks, of the different types available on the market, such as surgical and facial filtering masks (FFP1, FFP2 and FFP3), is also recommended. OBJECTIVES: The aim of this paper, within the Italian and European regulatory reference framework, is to suggest a rational application of existing methodologies that enable to know and assess the features and/or make a face mask intended to be used by the community. In addition to this, the study aims to provide a correct regulatory framework and useful information for a correct use and disposal of face masks. Another purpose is the assessment of the hygienic, sanitary and regulatory aspects related to the use and disposal of face masks. METHODS: The analysis of filtering masks is based on the review of scientific literature, the state of art of technology and the filtering means/materials available. Reference is made to filtering mechanisms and devices, the testing methods, the technical, manufacturing and performance features, and to the Italian and European regulatory reference framework. Reference is also made to the hygienic, sanitary and regulatory aspects related to the use and disposal of face masks. RESULTS: Surgical masks or, alternatively, filtering masks with a filtration efficiency between 90% and 95% for 3-µm particles, are the most practicable choice with minor contraindications. The reusable type of mask is conceptually superior compared to single-use masks, but cleaning procedures to be followed are quite complex and not always described in a clear way. CONCLUSIONS: The definition of rigorous and repeatable tests on mask filtration capacity, breathability, wearability, duration of use, regeneration, as well as safe disposal methods, are the main way to provide users with correct selection and use criteria. The results must be disclosed and disseminated quickly.

Is there an adequate alternative to commercially manufactured face masks? A comparison of various materials and forms.

BACKGROUND: There is a worldwide shortage of medical-grade face masks. Donning masks can play an important role in curbing the spread of SARS-CoV-2. AIM: To conclude whether there is an effective mask for the population to wear in public that could easily be made during a medical face mask shortage using readily available materials. METHODS: We determined the effectiveness of readily available materials and models for making a face mask. The outcomes were compared with N95/FFP2/KN95 masks that entered the Netherlands in April-May 2020. Masks were tested to determine whether they filtered a minimum of 35% of 0.3-µm particles, are hydrophobic, seal on the face, are breathable, and can be washed. FINDINGS: Fourteen of the 25 (combinations of) materials filtered at least 35% of 0.3-µm particles. Four of the materials proved hydrophobic, all commercially manufactured filters. Two models sealed the face. Twenty-two of the 25 materials were breathable at <0.7 mbar. None of the hydrophobic materials stayed intact after washing. CONCLUSIONS: It would be possible to reduce the reproduction rate of SARS-CoV-2 from 2.4 to below one if 39% of the population would wear a mask made from ePM1 85% commercially manufactured filter fabric and in a duckbill form. This mask performs better than 80% of the imported N95/FFP2/KN95 masks and provides a better fit than a surgical mask. Two layers of quilt fabric with a household paper towel as filter is also a viable choice for protecting the user and the environment.

[Validation of surgical masks during COVID19 emergency: activities at the University of Napoli Federico II]. / Validazione di maschere chirurgiche nella fase di emergenza COVID19: l'esperienza dell'Università degli Studi di Napoli Federico II.

SUMMARY: During COVID-19 pandemic crisis, Italian Government has approved Law Decree no. 18 of 17 march 2020, in which art. 15 allows enterprises to produce, import and commercialize surgical masks notwithstanding the current rules of product certification. It is just required that the interested enterprises send to the Italian National Institute of Health a selfcertification in which they declare the technical characteristics of the masks and that masks are produced according to the safety requirements. In this context, a technical-scientific unit was established at the University of Napoli Federico II to provide interested enterprises with state-of-the-art consultancy, testing and measurement services, adhering to rigorous scientific protocols. Characterization tests were carried out on 163 surgical masks and/or materials for their construction and they have enabled the identification of pre-screening criteria to simplify the procedure for evaluating surgical masks using methods for assessing the filtration efficiency of particles and aerosols. Based on experimental results, it has been observed that a filtration efficiency for particles with sizes larger that 650 nm (PFE>650) exceeding 35% might guarantees a bacterial filtration efficiency (BFE) higher than 95% while BFE values higher than 98% are obtained when the PFE>650 is larger than 40%. PFE measurement is extremely simpler with respect to BFE, the latter being time-consuming and requiring specific equipment and methods for its realization. Many tested materials have shown the capability to assure high filtration efficiencies but Spundonded-Meltblown-Spunbonded (SMS), that are layers of non-woven fabric with different weights of Meltblown, can simultaneously guarantee high particle filtration efficiencies with pressure drop values (breathability) in the limits to classify the surgical masks as Type II/IIR. In fact, the fabric products analyzed so far have not been able to simultaneously guarantee adequate BFE and breathability values. On the contrary, Spunbonds of adequate weights can virtually verify both requirements and accredit themselves as possible materials for the production of surgical masks, at least of Type I. Further studies are needed to verify the possibility of producing low-cost, reusable surgical masks that could meet the criteria of circular economy.

Filtration Efficiencies of Nanoscale Aerosol by Cloth Mask Materials Used to Slow the Spread of SARS-CoV-2.

Filtration efficiency (FE), differential pressure (ΔP), quality factor (QF), and construction parameters were measured for 32 cloth materials (14 cotton, 1 wool, 9 synthetic, 4 synthetic blends, and 4 synthetic/cotton blends) used in cloth masks intended for protection from the SARS-CoV-2 virus (diameter 100 ± 10 nm). Seven polypropylene-based fiber filter materials were also measured including surgical masks and N95 respirators. Additional measurements were performed on both multilayered and mixed-material samples of natural, synthetic, or natural-synthetic blends to mimic cloth mask construction methods. Materials were microimaged and tested against size selected NaCl aerosol with particle mobility diameters between 50 and 825 nm. Three of the top five best performing samples were woven 100% cotton with high to moderate yarn counts, and the other two were woven synthetics of moderate yarn counts. In contrast to recently published studies, samples utilizing mixed materials did not exhibit a significant difference in the measured FE when compared to the product of the individual FE for the components. The FE and ΔP increased monotonically with the number of cloth layers for a lightweight flannel, suggesting that multilayered cloth masks may offer increased protection from nanometer-sized aerosol with a maximum FE dictated by breathability (i.e., ΔP).

Can N95 Respirators Be Reused after Disinfection? How Many Times?

The coronavirus disease 2019 (COVID-19) pandemic has led to a major shortage of N95 respirators, which are essential for protecting healthcare professionals and the general public who may come into contact with the virus. Thus, it is essential to determine how we can reuse respirators and other personal protective equipment in these urgent times. We investigated multiple commonly used disinfection schemes on media with particle filtration efficiency of 95%. Heating was recently found to inactivate the virus in solution within 5 min at 70 °C and is among the most scalable, user-friendly methods for viral disinfection. We found that heat (≤85 °C) under various humidities (≤100% relative humidity, RH) was the most promising, nondestructive method for the preservation of filtration properties in meltblown fabrics as well as N95-grade respirators. At 85 °C, 30% RH, we were able to perform 50 cycles of heat treatment without significant changes in the filtration efficiency. At low humidity or dry conditions, temperatures up to 100 °C were not found to alter the filtration efficiency significantly within 20 cycles of treatment. Ultraviolet (UV) irradiation was a secondary choice, which was able to withstand 10 cycles of treatment and showed small degradation by 20 cycles. However, UV can potentially impact the material strength and subsequent sealing of respirators. Finally, treatments involving liquids and vapors require caution, as steam, alcohol, and household bleach all may lead to degradation of the filtration efficiency, leaving the user vulnerable to the viral aerosols.