Anaesthetists' current practice and perceptions of aerosol-generating procedures: a mixed-methods study.

The evidence base surrounding the transmission risk of 'aerosol-generating procedures' has evolved primarily through quantification of aerosol concentrations during clinical practice. Consequently, infection prevention and control guidelines are undergoing continual reassessment. This mixed-methods study aimed to explore the perceptions of practicing anaesthetists regarding aerosol-generating procedures. An online survey was distributed to the Membership Engagement Group of the Royal College of Anaesthetists during November 2021. The survey included five clinical scenarios to identify the personal approach of respondents to precautions, their hospital's policies and the associated impact on healthcare provision. A purposive sample was selected for interviews to explore the reasoning behind their perceptions and behaviours in greater depth. A total of 333 survey responses were analysed quantitatively. Transcripts from 18 interviews were coded and analysed thematically. The sample was broadly representative of the UK anaesthetic workforce. Most respondents and their hospitals were aware of, supported and adhered to UK guidance. However, there were examples of substantial divergence from these guidelines at both individual and hospital level. For example, 40 (12%) requested respiratory protective equipment and 63 (20%) worked in hospitals that required it to be worn whilst performing tracheal intubation in SARS-CoV-2 negative patients. Additionally, 173 (52%) wore respiratory protective equipment whilst inserting supraglottic airway devices. Regarding the use of respiratory protective equipment and fallow times in the operating theatre: 305 (92%) perceived reduced efficiency; 376 (83%) perceived a negative impact on teamworking; 201 (64%) were worried about environmental impact; and 255 (77%) reported significant problems with communication. However, 269 (63%) felt the negative impacts of respiratory protection equipment were appropriately balanced against the risks of SARS-CoV-2 transmission. Attitudes were polarised about the prospect of moving away from using respiratory protective equipment. Participants' perceived risk from COVID-19 correlated with concern regarding stepdown (Spearman's test, R = 0.36, p < 0.001). Attitudes towards aerosol-generating procedures and the need for respiratory protective equipment are evolving and this information can be used to inform strategies to facilitate successful adoption of revised guidelines.

Skin and respiratory ill-health attributed to occupational face mask use.

BACKGROUND: Face mask use in the workplace has become widespread since the onset of the Covid-19 pandemic and has been anecdotally linked to adverse health consequences. AIMS: To examine reports of adverse health consequences of occupational face mask use received by The Health and Occupation Research (THOR) network before and after the pandemic onset. METHODS: THOR databases were searched to identify all cases of ill-health attributed to 'face mask' or similar suspected causative agent between 1 January 2010 and 30 June 2021. RESULTS: Thirty two cases were identified in total, 18 reported by occupational physicians and 14 by dermatologists. Seventy-five per cent of cases were reported after the pandemic onset and 91% cases were in the health and social care sector. 25 of the 35 (71%) diagnoses were dermatological, the most frequent diagnoses being contact dermatitis (14 cases) and folliculitis/acne (6 cases). Of the seven respiratory diagnoses, four were exacerbation of pre-existing asthma. CONCLUSIONS: There is evidence of an abrupt increase in reports of predominantly dermatological ill-health attributed to occupational face mask use since the start of the pandemic. Respiratory presentations have also occurred.

Use of Micrococcus luteus to assess the quality of protection of respiratory organs using the pneumatic helmet with positive airflow.

In order to effectively protect from dangerous infectious agents, as well as coronavirus, the scientists of I. Horbachevsky Ternopil national medical university (Ukraine) developed a unique prototype of a mobile respiratory protection system with positive airflow - pneumatic helmet. AIM: To evaluate the bacterial permeability of the proposed concept model of the pneumohelmet in full and partial configuration. MATERIALS AND METHODS: With a generating device (compressor inhaler) an aerosol is created from bacterial suspension, which is directed to the inlet of the personal protective respiratory equipment. The outlet is directed at a Petri dish with meat-peptone broth. Evaluation of bacterial contamination is performed by calculating the colony-forming units by multiplying the indicator by the degree of dilution. The study is repeated with a partial configuration of the pneumatic helmet - the presence of only external, only internal filter or not using any filter components. RESULTS: The growth of Micrococcus luteus colonies on the placed nutrient medium when using the proposed conceptual model of the pneumatic helmet in full configuration was not obtained. Removal of the inner filter did not lead to a violation of the effectiveness of antibacterial protection, as bacteria were detected only on the outer side of filter No.2. The use of a conceptual model without filters made it possible to detect colonies of Micrococcus luteus on the medium and components of the device with the calculation of colony forming units in 3- and 4-fold dilutions. During 24 hours of operation, the bacterial load on the surface of the external filter increased significantly. However, no signs of malfunction of the pneumatic helmet were detected. CONCLUSIONS: The given results confirm the ability of the pneumatic helmet to counteract the penetration of bacteria from the environment during 6, 12, 24 hours of continuous operation. The protection was preserved even with partial configuration, which indicates the presence of a margin of reliability of this system.

Changes in skin characteristics after using respiratory protective equipment (medical masks and respirators) in the COVID-19 pandemic among healthcare workers.

BACKGROUND: The coronavirus disease-2019 (COVID-19) outbreak has presented unique dermatologic challenges due to respiratory protective equipment (RPE)-related skin conditions. OBJECTIVE: To objectively evaluate the effects of RPE including medical masks and respirators on the skin barrier by measuring various physiological properties of the skin. METHODS: A cross-sectional study was designed. Twenty healthy healthcare workers were included in this study. Skin parameters including skin hydration, transepidermal water loss (TEWL), erythema, sebum secretion, pH, and skin temperature were measured in the RPE-covered and RPE-uncovered areas of the face 4 and 8 hours after wearing RPE and 14 hours after not wearing RPE. RESULTS: Skin hydration, TEWL, erythema, pH, and skin temperature increased in the RPE-covered areas after wearing RPE for 4 and 8 hours. By contrast, in the RPE-uncovered areas, skin hydration decreased and TEWL, erythema, and pH showed minimal changes over time. Based on the repeated-measure analysis, the changes in skin physiological properties over time were significantly different between RPE-covered and RPE-uncovered areas. CONCLUSION: We observed that skin physiological characteristics change with the prolonged use of RPE such as medical masks and respirators. These changes may lead to various adverse skin reactions after long-term use.

A New Miniature Respirable Sampler for In-mask Sampling: Part 2-Tests Performed Inside the Mask.

This paper is the second in a series of two describing the performance of a miniature and low-weight respirable sampler designed to fit inside filtering facepiece (FFP) and half-mask type respirators. The first paper described the design of the miniature sampler and evaluated the particle and collection performance of the miniature sampler. This paper assesses its comparability with the traditional inward leakage measurement technique, and its safe use. Simultaneous mass measurements of a respirable sodium chloride aerosol were taken inside a total inward leakage chamber by a miniature sampler and by sodium flame photometry. Direct side-by-side comparison of the two methods yielded excellent correlation (R 2 = 0.99), as did comparison when sampling from inside four different masks when worn by a breathing Sheffield dummy head. In addition, comparison tests were carried out using three models of FFP worn by human volunteers both with and without the miniature sampler, in order to test whether or not the presence of the miniature sampler negatively affected the protection offered. The difference between the tests carried out with the miniature sampler and without the miniature sampler was not statistically significant (P = 0.3). In all cases, the masks performed within their protection class, whether the miniature sampler was fitted or not. We therefore conclude that the miniature sampler does not significantly affect the protection offered by the masks. The miniature sampler may prove a viable option for in-mask measurements of respirable dust where low air concentrations of hazardous material are expected.

A New Miniature Respirable Sampler for In-mask Sampling: Part 1-Particle Size Selection Performance.

The Health and Safety Laboratory has developed a miniature respirable sampler to gain a better understanding of the exposure of workers to hazardous substances when they are wearing respiratory protective equipment (RPE) or helmets with visors in the workplace. The study was in two parts and the first part, described herein, was to develop the sampler and test its collection characteristics. Assessment of the impact of the sampler on RPE safety and its comparability with traditional laboratory-based approaches to measure protection factors was discussed in a second article. The miniature sampler (weight-5.4g, length-13mm) was designed to fit into the space available between the nose and chin of an individual inside a filtering facepiece type mask and has a radially omnidirectional inlet with a porous foam particle selector that allows the collection of the respirable fraction on a downstream filter. The sampling efficiency was compared with the respirable convention. A close match with the respirable convention was obtained at a flow rate of 1 l min-1 and the 50% penetration cut off value (d 50) was 4.08 µm. After 3 hours sampling in high humidity (95%), the penetration curve had shifted towards smaller particle sizes (d 50 = 3.81 µm) with 88% of the calculated bias values within 10%. The miniature sampler measured respirable dust and crystalline silica mass concentrations comparable with performance of the Safety In Mines Personal Dust Sampler (SIMPEDS), commonly used in Great Britain, at a flow rate of 0.8 l min-1 The d 50 for the miniature sampler at 0.8 l min-1 (4.4 µm) is within 5% of the d 50 of the SIMPEDS at its prescribed flow rate of 2.2 l min-1 (4.2 µm). These results indicated that the miniature sampler was a good candidate to proceed with tests with RPE described in the second part of this series of two papers.

Evaluation of RPE-Select: A Web-Based Respiratory Protective Equipment Selector Tool.

This article describes the evaluation of an open-access web-based respiratory protective equipment selector tool (RPE-Select, accessible at http://www.healthyworkinglives.com/rpe-selector). This tool is based on the principles of the COSHH-Essentials (C-E) control banding (CB) tool, which was developed for the exposure risk management of hazardous chemicals in the workplace by small and medium sized enterprises (SMEs) and general practice H&S professionals. RPE-Select can be used for identifying adequate and suitable RPE for dusts, fibres, mist (solvent, water, and oil based), sprays, volatile solids, fumes, gases, vapours, and actual or potential oxygen deficiency. It can be applied for substances and products with safety data sheets as well as for a large number of commonly encountered process-generated substances (PGS), such as poultry house dusts or welding fume. Potential international usability has been built-in by using the Hazard Statements developed for the Globally Harmonised System (GHS) and providing recommended RPE in picture form as well as with a written specification. Illustration helps to compensate for the variabilities in assigned protection factors across the world. RPE-Select uses easily understandable descriptions/explanations and an interactive stepwise flow for providing input/answers at each step. The output of the selection process is a report summarising the user input data and a selection of RPE, including types of filters where applicable, from which the user can select the appropriate one for each wearer. In addition, each report includes 'Dos' and 'Don'ts' for the recommended RPE. RPE-Select outcomes, based on up to 20 hypothetical use scenarios, were evaluated in comparison with other available RPE selection processes and tools, and by 32 independent users with a broad range of familiarities with industrial use scenarios in general and respiratory protection in particular. For scenarios involving substances having safety data sheets, 87% of RPE-Select outcomes resulted in a 'safe' RPE selection, while 98% 'safe' outcomes were achieved for scenarios involving process-generated substances. Reasons for the outliers were examined. User comments and opinions on the mechanics and usability of RPE-Select are also presented.

Laboratory Animal Allergy in the Modern Era.

Laboratory animal workers face a high risk of developing laboratory animal allergy as a consequence of inhaling animal proteins at work; this has serious consequences for their health and future employment. Exposure to animal allergen remains to be the greatest risk factor although the relationship is complex, with attenuation at high allergen exposure. Recent evidence suggests that this may be due to a form of natural immunotolerance. Furthermore, the pattern of exposure to allergen may also be important in determining whether an allergic or a tolerant immune response is initiated. Risk associated with specific tasks in the laboratory need to be determined to provide evidence to devise a code of best practice for working within modern laboratory animal facilities. Recent evidence suggests that members of lipocalin allergens, such as Mus m 1, may act as immunomodulatory proteins, triggering innate immune receptors through toll-like receptors and promoting airway laboratory animal allergy. This highlights the need to understand the relationship between endotoxin, animal allergen and development of laboratory animal allergy to provide a safe working environment for all laboratory animal workers.

Respiratory protective equipment reduces occurrence of sensitization to laboratory animals.

BACKGROUND: Respiratory protective equipment (RPE) has been shown to reduce exposure to laboratory animal allergens, but there are no studies that have examined its effect on the development of sensitization. AIMS: To examine the effect of RPE on the risk of sensitization to laboratory animals. METHODS: Survey of UK laboratory animal workers conducted between 1999 and 2001. Information was recorded on the type of RPE used when first exposed to animals and at the time of the survey. Sensitization to rat urinary proteins was assessed using skin-prick tests and assays of specific serum IgE antibodies. RESULTS: There were 776 workers surveyed of whom 228 had been exposed for fewer than 5 years. Those more recently employed were more likely to have used RPE. In employees with <5 years of exposure the use of face masks at first employment was associated with a lower prevalence of sensitization, irrespective of the intensity of exposure to laboratory animals. This reduction was significant only in those who entered the animal house daily. CONCLUSIONS: The use of simple RPE at first exposure to laboratory animals may help to reduce the incidence of specific sensitization.

Initial evidence that skin health deteriorates for younger age groups and with increased daily use of face masks for healthcare professionals at a dental hospital in the United Kingdom.

OBJECTIVE: To determine the incidence and site of any adverse effects of wearing face masks via an online questionnaire. METHODS: Healthcare workers in a dental hospital who wear Respiratory Protective Equipment (RPE) were invited to participate. An online questionnaire was used to identify adverse effects as a result of wearing face masks and possible remedies. RESULTS: Red marks (72.1 %) and indentations (66.7 %) were the most frequently reported issues with increased use of the RPE. The bridge of the nose and cheeks were the most frequently reported sites of facial skin problems, such as blanching (54.1 % and 42.2 %, respectively) and pressure damage (42.3 % and 24.3 %, respectively). Overall perceived facial skin health deteriorated strongly and significantly (P < 0.001) following the use of RPE, where the mean skin health score (0 = best possible skin health and 10 = worst possible skin health) increased from 2.68 to 4.76. Broadly, there was increased discomfort with increased hours of use of RPE per day (P = 0.049). 71 % of participants said that they generally felt safe or very safe using RPE. CONCLUSION: The facial skin health of respondents deteriorated strongly after the use of RPE. Guidelines for using RPE should be made clearer. A greater range of face mask sizes or bespoke masks should be made available to improve the fit and wearability, as well as to reduce the frequency and incidence of surface skin problems. CLINICAL SIGNIFICANCE: This study has identified the factors influencing adverse skin reactions from face mask use, which can be used to inform face mask designers and manufacturers to improve the fit and wearability of face masks.

Prevention of COVID-19 in workers: preparation, precaution, and protection.

In May 2023 the World Health Organization (WHO) Director General announced the "end" of the COVID-19 Public Health Emergency of International Concern. Although the scale of the pandemic was unprecedented in living memory, it had not been unforeseen. Previous outbreaks of viral respiratory disease have shown important lessons regarding the need to protect healthcare workers (HCW), and research has also been undertaken into the relative effectiveness of control measures and their resource implications. Relevant guidance for worker protection, including HCW protection, which existed at the onset of the COVID-19 pandemic was disregarded both at international and national governmental levels. In many countries there were significant systemic flaws in strategy, culture, and resource availability, and hence in overall preparedness. When the pandemic struck, many experts and organizations advocated a precautionary approach with regard to worker protection, consistent with good occupational hygiene science, practice, and standards. In many Asian countries, protective measures were relatively stringent. However, many workers were left unprotected especially as the WHO, the United States, the United Kingdom, and other governments did not pursue adequate COVID-19 protective measures at work. As the pandemic progressed, improvements in protection were patchy. A notable lack of protection arose from the underestimation of the contribution of aerosol exposure to infection risks, particularly among HCWs providing routine care of potentially infectious patients. A disciplined strategy of source control, pathway control (such as ventilation), and receptor control notably Respiratory Protective Equipment is needed, as well as worldwide vaccination, to contend with this pandemic. Control measures appropriate to the risk of infections transmitted through the air will remain necessary in the longer term, as well as adaptations in the workplace to take account of long-term COVID-19 morbidity and new work practices.

Investigation of the effect of types of two different air filtered full-face masks used in chemical, biological, radiological, nuclear (CBRN) events on endotracheal intubation time: A randomized controlled study.

Introduction: Healthcare personnel may have to intervene with the injured using personal protective equipment depending on the environmental conditions.In injuries occurring in chemical, biological, radiological and nuclear (CBRN) events, healthcare personnel may have to intervene in the injured using personal protective equipment.The equipment used may lead to limitations, especially in cases requiring advanced airway intervention such as intubation. In this study, the effects of personal protective equipment on the intubation times of healthcare personnel were investigated. Method: This research was planned as a randomized prospective study, and the intubation procedure was performed on a simulation manikin. The intubation times were evaluated among three separate groups, 21 paramedic personnel in each. One group worked without masks, one used front filter masks, and the last worked with side filter masks. Results: The time spent for intubation by wearing a full-face mask with a side air filter and the intubation times performed without a mask were significantly different (p = 0.011). However, the intubation times of the groups using front and side air-filtered full-face masks were similar (p = 0.279). Conclusions: Health personnel should use a full-face mask with a front air filter as personal protective equipment during the interventions for the injured who need endotracheal intubation.

Use, failure, and non-compliance of respiratory personal protective equipment and risk of upper respiratory tract infections-A longitudinal repeated measurement study during the COVID-19 pandemic among healthcare workers in Denmark.

INTRODUCTION: Upper respiratory tract infections (URTI) are common and a common cause of sick-leave for healthcare workers, and furthermore pose a threat especially for patients susceptible to other diseases. Sufficient use of respiratory protective equipment (RPE) may protect both the workers and the patients. The COVID-19 pandemic provided a unique opportunity to study the association between use of RPE and URTI in a real-life setting. The aim of this study was to examine if failure of RPE or non-compliance with RPE guidelines increases the risk of non-COVID-19 URTI symptoms among healthcare workers. METHODS: In a longitudinal cohort study, we collected self-reported data daily on work tasks, use of RPE, and URTI symptoms among healthcare workers with patient contact in 2 Danish Regions in 2 time periods during the COVID-19 pandemic. The association between failure of RPE or non-compliance with RPE guidelines and URTI symptoms was analyzed separately by generalized linear models. Persons tested positive for severe acute respiratory syndrome coronavirus 2 were censored from the analyses. The 2 waves of data collection were analyzed separately, as there were differences in recommendations of RPE during the 2 waves. RESULTS: We found that for healthcare workers performing work tasks with a risk of transmission of viruses or bacteria, failure of RPE was associated with an increased risk of URTI symptoms, RR: 1.65[0.53-5.14] in wave 1 and RR: 1.30[0.56-3.03] in wave 2. Also non-compliance with RPE guidelines was associated with an increased risk of URTI symptoms compared to the use of RPE in wave 1, RR: 1.28[0.87-1.87] and wave 2, RR: 1.39[1.01-1.91]. Stratifying on high- versus low-risk tasks showed that the risk related to failure and non-compliance was primarily associated with high-risk tasks, although not statistically significant. DISCUSSION: The study was conducted during the COVID-19 pandemic and thus may be affected by other preventive measures in society. However, this gave the opportunity to study the use of RPE in a real-life setting, also in departments that did not previously use RPE. The circumstances in the 2 time periods of data collection differed and were analyzed separately and thus the sample size was limited and affected the precision of the estimates. CONCLUSION: Failures of RPE and non-compliance with RPE guidelines may increase the risk of URTI, compared to those who reported use of RPE as recommended. The implications of these findings are that the use of RPE to prevent URTI could be considered, especially while performing high-risk tasks where other prevention strategies are not achievable.

Evaluation of properties of elastomeric head straps of filtering facepiece respirators.

Frequent donning and doffing of filtering facepiece respirators (FFRs) can reduce their effectiveness due to the residual deformation of their elastic head straps. This study investigates the loss of elasticity of head straps during repeated use. Five elastomeric tapes were tested as FFR head straps, and their tensile strength was measured using a DU-100 dynamometer after repeated donning and doffing cycles. After eight consecutive uses, the protection factor drops significantly, requiring strap length adjustments to guarantee the specified level of user protection. The maximum tensile force of the elastomeric head straps causes residual elongation, which remains consistent after eight cycles. The study also establishes how strap elongation depends on the force and number of donning and doffing cycles. This knowledge is vital for designing better FFRs. Additionally, the research explores alternative materials for FFR construction to address strap elongation and its effects on performance and comfort.

Improvement of performance and function in respiratory protection equipment using nanomaterials.

Nanotechnology has become one of key areas for the current development and research. Nanotechnology focuses on matter at the nanoscale and is capable of using different approaches to produce nanomaterials, structures, devices, and systems. One of the concerns that have to be addressed is the adverse effects of exposure to pathogens and pollutants in different workplaces and environments. Respiratory protective equipment (RPE) is one of the personal protective equipment (PPE) utilized to reduce the risk of exposure to environmental or occupational respiratory hazards. Thus, various studies have been conducted for improving the functional properties of sorbents or filters in different kinds of RPE. Different categories of nanomaterials have been reported as effective agents for achieving this goal. The application of these nanomaterials in mask layers or respirators' cartridge could significantly increase the filtration efficiency, breathing comfort, and antibacterial/antiviral properties of the masks and respirators. The present study aimed to comprehensively review the nanomaterials used in different types of face RPE with emphasis on various properties of the utilized nanomaterials. The study also aimed to show an applied perspective for future research on this important subject.

Biomechanical and Physiological Evaluation of Respiratory Protective Equipment Application.

Purpose: Respiratory protective equipment is widely used in healthcare settings to protect clinicians whilst treating patients with COVID-19. However, their generic designs do not accommodate the variability in face shape across genders and ethnicities. Accordingly, they are regularly overtightened to compensate for a poor fit. The present study aims at investigating the biomechanical and thermal loads during respirator application and the associated changes in local skin physiology at the skin-device interface. Materials and Methods: Sixteen healthy volunteers were recruited and reflected a range of gender, ethnicities and facial anthropometrics. Four single-use respirators were evaluated representing different geometries, size and material interfaces. Participants were asked to wear each respirator in a random order while a series of measurements were recorded, including interface pressure, temperature and relative humidity. Measures of transepidermal water loss and skin hydration were assessed pre- and post-respirator application, and after 20 minutes of recovery. Statistical analysis assessed differences between respirator designs and associations between demographics, interface conditions and parameters of skin health. Results: Results showed a statistically significant negative correlation (p < 0.05) between the alar width and interface pressures at the nasal bridge, for three of the respirator designs. The nasal bridge site also corresponded to the highest pressures for all respirator designs. Temperature and humidity significantly increased (p < 0.05) during each respirator application. Significant increases in transepidermal water loss values (p < 0.05) were observed after the application of the respirators in females, which were most apparent at the nasal bridge. Conclusion: The results revealed that specific facial features affected the distribution of interface pressures and depending on the respirator design and material, changes in skin barrier function were evident. The development of respirator designs that accommodate a diverse range of face shapes and protect the end users from skin damage are required to support the long-term use of these devices.

Insecticide Filtration Efficiency of Respiratory Protective Equipment Commonly Worn by Farmers in Thailand.

Farmers are at a high risk of inhalation exposure when handling pesticides. Thai farmers usually protect themselves against pesticide exposure by wearing commercial respiratory protective equipment (RPE) available from rural community markets. However, scientific data regarding the pesticide filtration efficiency of RPE commonly worn by farmers is limited. Thus, this study aimed to investigate the efficiency of insecticide filtration of various RPE commonly worn by farmers in Thailand. The half facepiece respirator was used as a control to compare the results with other RPE. Ten types of RPE were selected for testing. The filtration efficiency of each RPE against insecticides was tested in a laboratory. The remarkable findings were that a surgical mask demonstrated the least filtration efficiency of all tested insecticides, with a range of 25.7-61.5%. The RPE available in rural markets of Thailand had a filtration efficiency within a range of 64.9-95.4%, whereas a half facepiece respirator was the most efficient in filtering insecticides, with a range of 96.5-98.9%. Therefore, our results suggest that the RPE most frequently worn by farmers may not provide adequate protection when compared with the respirator. However, considerations around RPE use in low-and middle-income countries and tropical climate conditions should be based on pesticide toxicity and practical use, ensuring balance between the risks from pesticide exposure and acceptance of PPE use.

Toward Mass Customization Through Additive Manufacturing: An Automated Design Pipeline for Respiratory Protective Equipment Validated Against 205 Faces.

Respiratory protective equipment (RPE) is traditionally designed through anthropometric sizing to enable mass production. However, this can lead to long-standing problems of low-compliance, severe skin trauma, and higher fit test failure rates among certain demographic groups, particularly females and non-white ethnic groups. Additive manufacturing could be a viable solution to produce custom-fitted RPE, but the manual design process is time-consuming, cost-prohibitive and unscalable for mass customization. This paper proposes an automated design pipeline which generates the computer-aided design models of custom-fit RPE from unprocessed three-dimensional (3D) facial scans. The pipeline successfully processed 197 of 205 facial scans with <2 min/scan. The average and maximum geometric error of the mask were 0.62 mm and 2.03 mm, respectively. No statistically significant differences in mask fit were found between male and female, Asian and White, White and Others, Healthy and Overweight, Overweight and Obese, Middle age, and Senior groups.

Comparative Performance Testing of Respirator versus Surgical Mask Using a Water Droplet Spray Model.

BACKGROUND: During the SARS-CoV-2 pandemic, there was shortage of the standard respiratory protective equipment (RPE). The aim of this study was to develop a procedure to test the performance of alternative RPEs used in the care of COVID-19 patients. METHODS: A laboratory-based test was developed to compare RPEs by total inward leakage (TIL). We used a crossflow nebulizer to produce a jet spray of 1-100 µm water droplets with a fluorescent marker. The RPEs were placed on a dummy head and sprayed at distances of 30 and 60 cm. The outcome was determined as the recovery of the fluorescent marker on a membrane filter placed on the mouth of the dummy head. RESULTS: At 30 cm, a type IIR surgical mask gave a 17.7% lower TIL compared with an FFP2 respirator. At 60 cm, this difference was similar, with a 21.7% lower TIL for the surgical mask compared to the respirator. When adding a face shield, the TIL at 30 cm was further reduced by 9.5% for the respirator and 16.6% in the case of the surgical mask. CONCLUSIONS: A safe, fast and very sensitive test method was developed to assess the effectiveness of RPE by comparison under controlled conditions.

Surgical Mask-the Saviour: from its Invention to the COVID-19 Era.

The earliest available evidence attributes the discovery of droplets as a mode of transmission of disease to Carl Flügge, a German bacteriologist, a contemporary of Emil Kocher, in 1897. This finding was instrumental in the development of the gauze mask introduced by Johann von Mikulicz Radecki in the same year. A surgical mask has become an indispensable tool in the armamentarium to fight the COVID 19 pandemic. Surgical masks which were once limited to the confines of healthcare setups are now donned by the members of the general public. It has become imperative that a healthcare worker selects the right kind of respiratory protective equipment to protect himself and his patients. The surgical mask has become essential, in a way, for survival.