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Effects of Long-Duration Wearing of N95 Respirator and Surgical Facemask: A Pilot Study
Abstract
The protection efficacy of facemasks and respirators has been well documented. The change of human nasal functions after wearing N95 respirator and surgical facemask is not known. In a parallel group study, we recruited 87 healthy healthcare workers. Each of the volunteers attended two sessions, and wore N95 respirator in session 1 (S1) and surgical facemask in session 2 (S2) for 3 hours. Mean minimum cross sectional area (mMCA) of the two nasal airways via acoustic rhinometry and nasal resistance via rhinomanometry were measured before and immediately after the mask wearing. Rhinomanometry was repeated every 30 minutes for 1.5 hours after the removal of masks. A questionnaire was distributed to each of the volunteers, during the 3 hours mask wearing period, to report subjective feelings on discomfort level of breathing activity. Among 77 volunteers who completed both the two sessions, the mean nasal resistance immediately increased upon the removal of surgical facemask and N95 respirator. The mean nasal resistance was significantly higher in S1 than S2 at 0.5 hour and 1.5 hours after removal of the masks (p<0.01). There is no statistical difference on mMCA before and after mask wearing in both sessions (p=0.85). The discomfort level was increasing with time while wearing masks, with significantly higher magnitude in S1 (p<0.001). There is an increase of nasal resistance upon removal of N95 respirator and surgical facemask potentially due to nasal physiological changes. N95 respirator caused higher post-wearing nasal resistance than surgical facemask with different recovering routines.
... Twelve of 22 studies (13,(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26) analysed the respiratory effects of wearing different respirators. These studies were conducted in Singapore (n = 2), Hong Kong (n = 1), the United States (n = 6), Australia (n = 1), Turkey (n = 1) and Fig. 4. The physical effects of personal protective equipment reported by study. ...
... Rebmann et al. (24) found that perceived exertion, shortness of breath, headache and light-headedness all increased over time with 22% of early PPE removals due to discomfort. Zhu et al. (26) also noted that mean comfort reduced as length of time wearing the N95 mask increased. Corley et al. (12) found staff (in practice) were expected to wear full PPE for 12 h shifts with a 1-1.5-h break (reflecting real life practice), and staff reported significant difficulties with this as time increased. ...
Background: The COVID-19 pandemic has required healthcare workers to wear personal protective equipment (PPE), and although there is increasing awareness of the physical effects of wearing PPE, the literature has yet to be synthesised around this topic. Methods: A scoping review was conducted to synthesise existing literature on the physical effects of wearing PPE and identify gaps in the literature. A comprehensive search strategy was undertaken using five databases from 1995 to July 2020. Results: A total of 375 relevant articles were identified and screened. Twenty-three studies were included in this review. Studies were conducted across 10 countries, spanning 16 years from 2004 to 2020. Half (13/23) were randomised controlled trials or quasi-experimental studies, five surveys, two qualitative studies, two observational or case series and one Delphi study. Most (82%, 19/23) studies involved the N95 mask (either valved or unvalved). None specifically studied the filtering facepiece 3 mask. The main physical effects relate to skin irritation, pressure ulcers, fatigue, increased breathing resistance, increased carbon dioxide rebreathing, heat around the face, impaired communication and wearer reported discomfort. Few studies examined the impact of prolonged wear (akin to real life practice) on the physical effects, and different types of PPE had different effects. Conclusions: The physical effects of wearing PPE are not insignificant. Few studies examined the physiological impact of wearing respiratory protective devices for prolonged periods whilst conducting usual nursing activity. No ideal respirators for healthcare workers exist, and the development of more ergonomic designs of PPE is required.
... Both N95 and surgical face masks have been shown to reduce cardiopulmonary exercise capacity [22]. Studies have shown changes to the nasal airway resistance and minimum cross-sectional area in the time after wearing N95 or surgical masks [23]. Panic prone individuals have a potential risk of respiratory discomfort when wearing respiratory protective devices. ...
... Whilst several existing studies illustrate the discomforts levels experienced by mask-wearing frontline healthcare Infection, Disease & Health 26 (2021) 145e151 workers [23], to our knowledge no other articles report the public perception to mask-wearing. Our study is one of the first to distinguished various types of discomforts experienced by individual mask-wearers across various age groups and ethnicity, providing mask-producing organizations valuable market research allowing mitigation of these discomforts for specific demographic groups, with the aim to make masks more comfortable for mass usage. ...
Background
Despite increasing evidence to support mask effectiveness in mitigating the spread of COVID-19, there is still raging controversy regarding the use of masks. Evaluation of public perceptions, attitudes and the individuals’ experience towards mask-wearing is integral to ensuring reasonable compliance and allows authorities to address concerns held by the population.
Methods
A cross-sectional survey of lay-people was conducted within a high volume tertiary level institution in Singapore, from 16 October to 16 November 2020. Surveys administered evaluated five questions: 1) duration of mask wear per day, 2) mask-type used, 3) perceived necessity, 4) discomfort level experienced and 5) causes for discomfort.
Results
Out of 402 respondents, 67.2% primarily wore disposable surgical masks. 72% felt mask-wearing was necessary to control COVID-19 transmission. 78.4% reported discomfort while wearing masks, with mean discomfort levels of 4.21 out of 10. Impairment to breathing and communication difficulties were the most common discomforts faced. Younger respondents complained of higher incidence of dermatological issues and sweating (p < 0.05). Respondents who wore masks for longer duration reported higher incidence of dermatological issues (p = 0.001) and sweating (p = 0.032).
Conclusion and Relevance
Even with an available vaccine, adjunctive public health measures such as mask-wearing will likely continue in order to curb COVID-19 transmission. Experience from past pandemics is likely to propagate self-protective behavior within a community. Our study identified several common mask-wearing discomforts, allowing respective organizations valuable market feedback for research and development. With appropriate public attitudes, effective mask-wearing compliance can be attained in a concerted effort against the coronavirus.
... Physiological changes such as increased respiratory resistances were observed after 3 hours of use. 22 Headache associated with filter mask use could be included according to ICHD-3 11 in the section on headaches due to homeostatic disorders where those related to alteration of oxygen and CO 2 partial pressure parameters are included. Another phenomenon probably related to the physiopathology of headache after PPE use is the external compression that it generates, as recently reflected by the group of Ong et al. 23 In most cases there is a temporal relationship between the use of devices and the headache, as well as the topographical location of the headache. ...
... There are several examples in the literature that would be consistent with this mechanism. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] The last factor to be mentioned is the level of anxiety or stress. Multiple ways of relating stress and headache have been described, either as 'de novo' or as exacerbation in an individual with primary headache. ...
Objectives The pandemic caused by the new coronavirus (COVID-19) has changed care activities of health professionals. We analysed the possible association between the appearance of ‘de novo’ headache according to the type of mask used, the related factors and the impact of the cephalalgia on health professionals.
Methods Cross-sectional study in a tertiary hospital in Extremadura, Spain. We provided an online questionnaire to healthcare workers during the period of maximum incidence of COVID-19 in our setting.
Results The subjects are n=306, 244 women (79.7%), with an average age of 43 years (range 23–65). Of the total, 129 (42.2%) were physicians, 112 (36.6%) nurses and 65 (21.2%) other health workers. 208 (79.7%) used surgical masks and 53 (20.3%) used filter masks. Of all those surveyed, 158 (51.6%) presented ‘de novo’ headache. The occurrence of a headache was independently associated with the use of a filter mask, OR 2.14 (95% CI 1.07 to 4.32); being a nurse, OR 2.09 (95% CI 1.18 to 3.72) or another health worker, OR 6.94 (95% CI 3.01 to 16.04); or having a history of asthma, OR 0.29 (95% CI 0.09 to 0.89). According to the type of mask used, there were differences in headache intensity, and the impact of a headache in the subjects who used a filter mask was worse in all the aspects evaluated.
Conclusion The appearance of ‘de novo’ headache is associated with the use of filter masks and is more frequent in certain healthcare workers, causing a greater occupational, family, personal and social impact.
... It was generally accepted that N95 respirator is more effective for filtration compared to facemask. 2 A pressure injury is localised damage to the skin and underlying soft tissue, usually over a bony prominence. It occurs as a result of intense or prolonged pressure or pressure in combination with shear. ...
... 4 The long term physiological effect of the N95 has been previously described. 2 However, there has not been any report of nasal bridge pressure ulcers associated with the N95 respirator. We describe a series of five HCW who presented to us with nasal pressure ulcers within a span of 2 weeks. ...
... In a study [37] reviewing epidemiological data on OSA, M:F = 2:1 was in close accordance with our study. A pilot study [38] during covid-19 pandemic showed a massive female preponderance (M:F = 1:5.4). Most of the candidates were married (n = 79,81.44%). ...
COVID-19 caused by SARS-CoV2 has reached pandemic proportions. The fear of Covid-19 has deterred many to abandon efforts for seeking timely medical help. In this setting, Obstructive sleep apnea (OSA)-like covid/non-covid cohorts have presented. Atypical pathologies can present like OSA and take the clinician unawares. With this series of misfits suffering silently, it would be unwise to underestimate its impact on quality-of-life (QOL). To determine the effect on quality-of-life by pathologies mimicking OSA and assess Covid-19 as a cause for delayed presentation. This was a prospective cross-sectional study. 127(N). Recent onset of symptoms of OSA. Study duration March 2020 to September 2021. Pittsburgh Sleep Quality Index (PSQI) screening done. Study criteria defined. Sleep parameters calculated. Primary surgical intervention given. Non-responders were put on CPAP therapy. QOL assessment done with sf-36 and SAQLI. Fear of Covid-19 scale (FCV-19S) quantified to study cause for temporal delay. Correlations computed. Level of Evidence—Level 3. 97 candidates completed study. Demographic and anthropometric details noted. Mean range was 43.85 ± 11.39 years. Male predominance. Overall AHI-19.73 ± 8.72. Moderate impact on QOL by sf-36/SAQLI. 78n Primary surgical candidates fared well. Polysomnography (PSG) and Continuous positive airway pressure (CPAP) titration/trial characteristics for 19n available. Statistically significant improvement in QOL after treatment completion. Correlations were meaningful. Body Mass Index (BMI) as a single factor was not influential on OSA-mimickers. Fear of Covid-19 significantly impacted emergency medical aid acquisition. OSA mimicking atypical airway pathologies may need emergent treatment not only from a surgical point-of-view but also from the QOL of the patient. On the contrary, these also unmask sub-clinical OSA, especially in patients with low/normal BMI. This category of recent onset OSA, if fortunately picked up at the earliest possible presentation, may hopefully not go through the significant QOL impact suffered by chronic OSA candidates.
... These are tight-fitting masks and seal the nose and mouth and prevent the wearer for inhalation of smaller infectious particles. [2,3] Despite the protective function of N95 masks, other discomforts like effects on respiratory microclimate, oxygen saturation, heart rate, and individual sensational hazards, namely, breathlessness, headache, and suffocation, also need to be examined. [4][5][6] N95 masks are likely to induce different temperatures and humidification on outer and inner mask surface; it is likely to be because of lower air permeability and water vapor permeability in N95 respirator. ...
Background and Aims: N95 mask being an essential element of personal protective equipment to be worn by health-care workers (HCWs) may lead to adverse effects and physiological stress as HCWs have to wear it for prolonged hours. Therefore, we planned to conduct a study in our intensive care unit staff to look for the effects of N95 masks on their health as well as to plan recommendations to ease them.
Material and Methods: We conducted this study on our intensive care unit nursing staff and HCWs. We noted their oxygen saturation and heart rate at baseline as well as after 1 h, 2 h, 3 h, and 6 h of duty along with their subjective sensations. Institutional ethical clearance for the same was taken. Collected data were entered in MS Excel database and analyzed using SPSS version 20.0. Fisher's Z test was applied for comparing proportion and analysis of variance for comparing two means.
Results: One hundred and nine HCWs participated in this, out of which 93 (85.3%) were females and 16 (14.7%) were males. Eighty-four (77.1%) participants were below 40 years. Twenty-three participants (21.1%) were overweight and 37 (33.9%) were obese. There was no significant drop in saturation and rise in heart rate during these hours.
Conclusions: On comparing subjective sensations of HCWs, our study found that feeling of uneasiness was found more in less than 40 years age group as compared to more than 40 years. N95 masks were found to have no impact on cardiovascular system and do not lead to hypoxia while working routinely even for prolonged hours.
... The typical use time of a surgical mask is 6 h (21,600 s), whereas an N95 respirator generally lasts much longer (here we tested 12 h or 43,200 s) because it is 5−10 times more expensive than a surgical mask. 18 Moreover, as mentioned above, the airflow rate over masks in flow cells was similar to the air velocity in natural convection, 16 so the dilution and dispersion of VOCs emitted from masks during airing out in an indoor environment can be simulated. The concentrations of VOCs emitted at different times of airing out were compared with the World Health Organization (WHO) standards for indoor air quality (IAQ). ...
... It is widely used in both medical and industrial environments because of its high filtration capacity: 99.5% for particles larger than 0.75µm and 95% (smallest filtration) for particles between 0.1 and 0.3µm [7, 8,9]. However, users report a high lack of comfort, especially for long-term wear [10]. Breathing and speaking are also a problem. ...
... Therefore, it seems that the staff should only use the protective equipment in highrisk wards of health care sittings during work time and prevent over-use of this equipment to avoid and decrease adverse the skin effects. In this regard, Zhu et al. [11] showed that long-term use of N95 respirator and surgical face mask among health care staff can cause nasal physiological changes, which is consistent with our findings. The lowest rate of the skin symptoms was observed in the feet and trunk, which is clearly related to the lack of exposure to the disinfectants and lack of direct contact with the protective equipment. ...
... Throughout the COVID-19 pandemic, there has been high demand for personal protective equipment (PPE) in the United States, notably N95 respirators [1,2]. These respirators are a critical piece of PPE considered to be critical in preventing inter-human infection from the virus [3,4]. Even in November 2020, ten months into the pandemic, 61% of facilities reported shortages of PPE [5]. ...
There has been high demand for personal protective equipment (PPE) during the COVID-19 pandemic, especially N95 respirators. Unfortunately, at the early stage of the pandemic, the supply could not meet the demand for N95 respirators, leading to a shortage and unsafe reuse of this form of PPE. We developed the Moldable Mask to ease the demand for N95 respirators by creating a 3D-printed mask that uses a piece of N95 material as a filter. A sheet of N95 material could be used or one N95 respirator to be turned into two masks. The main feature of the mask is the ability to easily mold it in hot water to create a custom fit for each user. It can also be easily assembled at home with affordable materials. The final mask design was qualitatively fit tested on 13 subjects, with all subjects showing an improvement in fit with the hot water molding technique and 10 (77%) subjects passing the fit test. This shows that the Moldable Mask is a viable option for a safe, affordable N95 alternative when N95 mask supply is strained.
... Buna ek olarak Zhu ve ark., yaptıkları çalışmada, benzer sonuçlar bulmuşlar ve maske takmanın solunum direncine neden olduğunu bildirmişlerdir. 31 Zhao ve ark., yaptıkları bir başka çalışmada, tıbbi maskenin oksijen alımını kısıtlayabildiğini söylemişlerdir. 32 Bu bulgular, araştırmamızda elde ettiğimiz bulgularla benzerlik göstermektedir. ...
... Previous research has demonstrated that using N95 face masks results in an increase in the nasal resistance which persists for up to 1.5 hours after removal. 6 Altered nasal physiology It has also been reported that inhalation of dry air results in prolongation of the nasal mucociliary clearance rates. 14 Courtney and Bax opined that the nasal mucociliary clearance should improve with the use of masks as they increase the relative humidity of inspired air. 3 However, we observed prolongation of the STT in N95 users. ...
Objective
It has been shown that prolonged use of face masks results in physiological changes in the nasal cavity. The objective of this study was to examine the effect of prolonged use of face masks on nasal mucociliary clearance (NMC).
Methods
A single group pre-post study was conducted to determine the effects of prolonged use of N95 face mask (≥4 hours) on the NMC rates in health care workers. Saccharin transit time (STT) was used to measure the NMC. STT before and after using an N95 mask for at least 4 hours was measured for all participants in controlled conditions of temperature and humidity.
Results
Forty-eight volunteers (20 female and 28 male) completed the study after the enrollment of 57 volunteers. The mean STT before mask use was 580.27 ± 193.93 seconds (95% CI; 523.95-636.58 seconds) and after mask use was 667.47 ± 237.42 seconds (95% CI; 598.53-736.42 seconds). There was significant prolongation of the NMC after prolonged use of N95 mask on performing the paired t-test ( P = .002). The mean prolongation was 87.20 ± 184.97 seconds with an actual effect size of 0.40. Ambient temperature and humidity were not significantly different at the two test instances.
Conclusion
Use of the N95 face masks for 4 hours results in prolongation of the nasal mucociliary clearance as measured by STT. Susceptibility to any respiratory infection may be increased following doffing of the personal protective equipment, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) itself.
... Respirators may appear to be rather simple, but they can interfere with : Studies have demonstrated side effects associated with the use of particulate respirators including facial dermatitis from the respirator components, increased work of breathing, respiratory fatigue, impaired work capacity, increased oxygen debt, early exhaustion at lighter workloads, elevated levels of CO2, increased nasal resistance, and increased noncompliance events leading to self-contamination (adjustments, respirator or face touches, under-therespirator touches, and eye touches). NIOSH 13,14,15,16,17,18,19 reported that the N95 filtering facepiece respirators had the highest inhaled CO2 concentrations (3.6%) and the lowest mean inhaled O2 concentration (16.8%). 20 Our data indicates a no significant drop in O2 concentration at the initiation of treatment with either type of the mask used ( . ...
Introduction: Filtering facepiece respirators (FFR) are the most commonly used with the N95 FFR being the most popular overall. The number 95 signifying that it is at least 95% efficient in filtering particles. Elastomeric respirators are available as alternatives to disposable half mask filtering facepiece respirators (FFRs), such as N95 FFRs, comparatively elastomeric respirators have been found to have 60% higher filtration performance. Previous reports highlighted that difficulty in breathing resulted in limited tolerability when the N95 face mask was used for a prolonged period. Objectives: To evaluate and compare the physiological effect of N95 FFR and 3M elastomeric respirators on dental surgeons. Methodology: The study included 48 participants divided into 2 groups of 24 subjects each. Group 1 and Group 2 included participants using 3M elastomeric respirators and N95 FFR and respectively. Non-smokers and systemically healthy participants were included and the oxygen saturation, pulse rate and respiratory rate readings were taken before the start of the procedure, 30 mins after the start of the procedure and after the completion of procedure with a standard fingertip pulse-oximeter. Conclusion: N95 FFR is acknowledged by the majority of dental professionals, although the majority experienced several perceived side effects. 3M elastomeric respirators have few advantages over the conventional N95 masks and can be an effective alternative to N95 FFR.
... In a study conducted with 87 participants, who used a N95 mask in the first session and a surgical mask in the second session, received acoustic rhinometry and rhinomanometry tests before and after the mask. No difference was found in terms of mean minimum cross-sectional area values obtained before and after the mask in both sessions [27]. However, in this study, the duration of use of masks was three hours. ...
Purpose
The aim of this study was to reveal the effect of N95 and surgical masks on mucociliary clearance function and sinonasal complaints.
Methods
Sixty participants were enrolled in this study, including 30 people in N95 mask group and 30 people in surgical mask group. Two interviews, three days apart, were performed with all participants. The participants were asked not to use any mask before the first interview while they were asked to use the determined mask just before the second interview for 8 h. In both interviews, the mucociliary clearance times (MCTs) were measured and participants were asked to score ten distinct sinonasal complaints using visual analog scale (VAS). Data obtained from first interview were named pre-mask data, data obtained from second interview were called after-mask data. In both groups, pre-mask MCTs and VAS scores were compared with after-mask MCTs and VAS scores.
Results
After-mask MCTs (mean = 13.03 ± 6.05 min) were significantly longer than pre-mask MCTs (mean = 10.19 ± 4.21 min) in N95 mask group (p = 0.002). No significant difference was found between after-mask and pre-mask MCTs (mean = 12.05 ± 5.21 min, mean = 11.00 ± 5.44 min, respectively) in surgical mask group (p = 0.234). When after-mask VAS scores were compared with pre-mask VAS scores, it was found that N95 mask use increased nasal blockage and postnasal discharge, surgical mask usage increased nasal blockage.
Conclusion
While the use of N95 mask leads to nasal blockage and postnasal discharge, surgical mask use results in nasal blockage. N95 masks cause impairment in mucociliary clearance function. But all these effects are mild. Surgical masks have not been found to have any effect on mucociliary clearance function.
... It should be noted that formula (10) takes into account the decreasing value in the disk on the filter caused by increasing its area due to changes in the initial filtration rate, which is determined based on air flow according to the physical load of the worker when performing production functions [56]. One can see good quantitative and qualitative agreement between the experimental data and the theoretical curves, which shows the fact that the model equation is suitable for calculating the pressure drop on the respirator during breathing, while the index of dissimilarity according to Student's test showed a discrepancy of up to 20%. ...
In this paper, a solution to the problem of the change in the pressure drop in a respirator filter during cyclic air motion is suggested since the current theory of filtering is based on steady-flow processes. The theoretical dependence of the pressure drop in the respirator filter on air flow rate is determined, which is represented by the harmonic law, which characterizes the human respiration process during physical work. For the calculation, a filter model was used, which is represented by a system of parallel isolated cylinders with a length equal to the total length of the filter fibres surrounded by porous shells formed by a viscous air flow field, with a size determined by the equal velocities of the radial component of air flow and undisturbed flows. The flow-around process in the proposed model of air flow through the respirator filter is described by the Brinkman equation, which served to establish the total air flow resistance in the proposed system under conditions of velocity proportionality. It consists of two parts: the first characterizes the frictional resistance of the air flow against the surface of the cylinder, which imitates the filter fibre; the second—the inertial part—characterizes the frequency of pulsations of respiratory movements during physical performance. The divergence of the analytical results and experimental studies is no more than 20%, which allows the use of the established dependence to estimate the change in pressure drop in a respirator filter made of filter material “Elephlen” when the user carries out different physical activities. This allows the period of effective protective action of respirators with different cycles of respiration during physical activities to be specified, which is a very serious problem that is not currently regulated in health and safety regulations, and it also allows the prediction of the protective action of filters and respiratory protection in general.
... Respiratory infections and asthma were significantly more common among veils users (p < 0.00001 and p < 0.0003, respectively, probably secondary to infection (Ahmad et al., 2001). Discomfort levels increase with duration of time wearing masks and nasal resistance increases upon removal of an N-95 mask or a surgical facemask, potentially due to nasal physiological changes (Zhu, Lee, Wang, & Lee, 2014). Masks wearing, is a political, sociological decision. ...
Objectives
We aimed to analyze factors impacting the Covid-19 epidemic on a macro level, comparing multiple countries across the world, and verifying the occurrence at a micro level through cluster analysis.
Design
Statistical analysis of large datasets.
Methods
We used publicly available large world datasets (1-11). Data was transformed to fit parametric distributions prior to statistical analyses, which were performed with Student’s t-test, linear regression and post-hoc tests. Especially for ordinary least squares regression, natural logarithmic transformations were done to remediate normality violations in the standardized residuals.
Results
The severity of the epidemic was most strongly related to exposure to ultraviolet light and extrapolated levels of vitamin D and to the health of the population, especially with regards to obesity. We found no county with an obesity level < 8% with a severe epidemic. We also found that countries where the population benefited from sun exposure or vitamin D supplementation and spent time outside fared well. Factors related to increased propagation of the virus included the use of heating ventilation and air conditioning (HVAC), population density, poorly aerated gatherings, relative humidity, timely policies of closing clustering places until aeration was improved, and daily amount of ridership on public transportation, especially subways. Population lockdowns, masks, and blood type did not provide much explanatory power. The excess mortality observed is within the ranges of severe past influenza epidemics of 2016/2017 or 1999/2000.
Conclusions
Our study suggested that prevention measures should be directed to improving aeration systems, enhancing diets and exercise, and ensuring adequate levels of vitamin D. Further research on masking is indicated as our study could not separate policies from how well they were actually followed.
Funding
This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors’
Strengths and Limitations of the Study
The Study examines large datasets across countries to look for macrotrends in management of the Covid-19 outbreak.
The Study cannot necessarily establish causation but rather correlation.
The Study raises some novel possibilities for further studies in relation to country-wide and individual-level susceptibility to Covid-19 and to other epidemics in general.
The Study raises questions about some political policies based upon country-level comparisons and suggests some areas for exploration of prevention policies.
... Zhu et al. 80 reported another investigation on the effect of long duration wearing of N95 and surgical facemasks on upper airway functions. A total of 47 volunteers of National University Hospital of Singapore participated for the study. ...
In the unfortunate event of current ongoing pandemic COVID-19, where vaccination development is still in the trial phase, several preventive control measures such as social distancing, hand-hygiene, and personal protective equipment have been recommended by health professionals and organizations. Among them, the safe wearing of facemasks has played a vital role in reducing the likelihood and severity of infectious respiratory disease transmission. The reported research in facemasks has covered many of their material types, fabrication techniques, mechanism characterization, and application aspects. However, in more recent times, the focus has shifted towards the theoretical investigations of fluid flow mechanisms involved in the virus-laden particles prevention by facemasks. This exciting research domain aims to address the complex fluid transport that led to designing a facemask with a better performance. This review paper discusses the recent updates on fluid flow dynamics through the facemasks. Key design aspects such as thermal comfort and flow resistance are discussed. Furthermore, the recent progress in the investigations on the efficacy of facemasks for prevention of COVID 19 spread and the impact of wearing facemasks are presented.
... In a controlled clinical study, it was seen that those who were wearing N 95 mask, their effect on pregnant healthcare workers lead to the impediment of the gaseous exchange and it led to an additional workload on the metabolic system [4]. Wearing N 95 mask for a long duration may induce physiological stress which can make regular tasks difficult and may cause a headache amongst health care providers, due to the respiratory microclimate change surrounding the mask [5]. It was seen that the nasal resistance was not recovered even after 1.5 hours removal of the facemask. ...
The role of the surgical mask during COVID-19 pandemic is undoubtedly very vital in preventing infections. A review of the evolution of the face mask from the animal bladder of the past to the present N 95 is being done with an emphasis on the importance and problems currently faced by the surgical community due to constant wearing of N 95 mask in the hospital. Though N 95 mask is the ideal mask during Coronavirus pandemic, there are a few issues like carbon dioxide retention and headache which is hampering its prolonged use.
... Whilst the prolonged use of face mask may not lead to significant hypoxia and hypercapnia under normal use at rest, but can do so during stress [2] or exercise [3], and is associated with increased respiratory efforts, reduced work performance [4], adverse effects such as discomfort [5] and headaches [6], especially in individuals with increased basal metabolic demands such as pregnancy [7]. Such physiological changes can be observed with simple surgical masks [2] but is exacerbated with N95 [8] or full-face respirators [9]. ...
The mandatory use of facemasks is a public health measure implemented by various countries in response to the novel coronavirus disease 19 (COVID-19) pandemic. However, there have been case reports of sudden cardiac death (SCD) with the wearing of facemasks during exercise. In this paper, we hypothesize that exercise with facemasks may increase the risk of ventricular tachycardia/ventricular fibrillation (VT/VF) leading to SCD via the development of acute and/or intermittent hypoxia and hypercapnia. We discuss the potential underlying mechanisms including increases in adrenergic stimulation and oxidative stress leading to electrophysiological abnormalities that promote arrhythmias via non-reentrant and reentrant mechanisms. Given the interplay of multiple variables contributing to the increased arrhythmic risk, we advise avoidance of a facemask during high intensity exercise, or if wearing of a mask is mandatory, exercise intensity should remain low to avoid precipitation of lethal arrhythmias. However, we cannot exclude the possibility of an arrhythmic substrate even with low intensity exercise especially in those with established chronic cardiovascular disease in whom baseline electrophysiological abnormalities may be found.
... One of the systematic reviews commented about the harms of particulate respirators, especially when worn for prolonged periods [57]. Other studies have demonstrated side effects associated with the use of particulate respirators including facial dermatitis from the respirator components, increased work of breathing, respiratory fatigue, impaired work capacity, increased oxygen debt, early exhaustion at lighter workloads, elevated levels of CO 2 , increased nasal resistance, and increased noncompliance events leading to self-contamination (adjustments, respirator or face touches, under-the-respirator touches, and eye touches) [61][62][63][64][65][66][67]. These side effects are not encountered with the same frequency with the appropriate use of medical masks. ...
Abstract Currently available evidence supports that the predominant route of human-to-human transmission of the SARS-CoV-2 is through respiratory droplets and/or contact routes. The report by the World Health Organization (WHO) Joint Mission on Coronavirus Disease 2019 (COVID-19) in China supports person-to-person droplet and fomite transmission during close unprotected contact with the vast majority of the investigated infection clusters occurring within families, with a household secondary attack rate varying between 3 and 10%, a finding that is not consistent with airborne transmission. The reproduction number (R0) for the SARS-CoV-2 is estimated to be between 2.2–2.7, compatible with other respiratory viruses associated with a droplet/contact mode of transmission and very different than an airborne virus like measles with a R0 widely cited to be between 12 and 18. Based on the scientific evidence accumulated to date, our view is that SARS-CoV-2 is not spread by the airborne route to any significant extent and the use of particulate respirators offers no advantage over medical masks as a component of personal protective equipment for the routine care of patients with COVID-19 in the health care setting. Moreover, prolonged use of particulate respirators may result in unintended harms. In conjunction with appropriate hand hygiene, personal protective equipment (PPE) used by health care workers caring for patients with COVID-19 must be used with attention to detail and precision of execution to prevent lapses in adherence and active failures in the donning and doffing of the PPE.
... Some wearers also complain of headache, lightheadedness, and difficulty communicating. 19 Research had confirmed that such changes minimally affect physical work performances. 20 Second PPEs is face shield. ...
Background: COVID-19 has been regarded as a new pandemic in the world. This disease is highly contagious and can be transmitted easily through droplets and air. This matter is considered as a red flag to all dentists all over the globe. Until today, there is only a few specific guideline in regards to dental practice during and after the pandemic. The protocol only revolves around the limitation of patients’ appointments and using level 3 personal protection equipment. There is no specific mention on the preparation method of the practice room especially in Indonesia. Purpose: This study aims to review literature on infection control in dental settings during COVID-19 pandemic and discuss possible recommendations based on available evidence. Review: The review also discussed the background of COVID-19, transmission, clinical findings, physicochemical properties, and cross infection in dental practice. Despite the usage of personal protective equipment, the rooms need to be set to specific requirement to reduce contamination inside the room. Until today, COVID-19 transmission must be prevented with the best method available. Conclusion: No single protocol may fully guarantee the safety of the patients and dental workers. We suggest to combine the protocol listed above to minimize to self and cross-contamination ’new normal’ practice.
... 23,24 Additionally, the tight seal needed for N95s with their nonadjustable bands can cause significant facial trauma and respiratory compromise to health care workers over repeated use or after procedures of long duration. 25,26 For standard airborne precautions, N95 masks are appropriate for respiratory protection. However, for surgeons involved in recurrent or longduration high-risk AGPs, enhanced respiratory protection with filters certified as 99, 100, or HEPA (high-efficiency particulate air) may be appropriate in these circumstances. ...
As rhinologists return to practice amid SARS-CoV-2, special considerations are warranted given the unique features of their subspecialty. Rhinologist manipulation of nasal tissue, proximity, and frequent aerosol-generating procedures (AGPs) create high risk for infection transmission. There are 4 areas of special consideration to mitigate risk: (1) previsit planning for risk stratification/mitigation, (2) appropriate personal protective equipment, (3) preprocedural testing, and (4) environmental controls. During previsit planning, risk factors of the patient and procedures are considered. High-risk AGPs are identified by duration, proximity, manipulation of high–viral load tissue, and use of powered instrumentation. Appropriate personal protective equipment includes selection of respiratory and eye protection. COVID-19 testing can screen for asymptomatic carriers prior to high-risk procedures; however, alternative testing methods are required in rhinologic patients not eligible for nasopharyngeal testing due to nasal obstruction or skull base defects. Last, AGPs in rhinologic practices require considerations of room air handling and environmental controls.
... However, the study respondents have reported practical problems in wearing masks for prolonged periods of time, as needed in high prevalence settings. Other studies have reported association of discomfort and headache with prolonged use of masks [27,28]. The institute should 6 Tuberculosis Research and Treatment formulate a policy for using N-95 masks and motivate and monitor its use among the residents. ...
Setting. Government tertiary health care center in India. Objective. To understand the perceptions of medical residents about their
risk of developing TB in the workplace. Design. Cross-sectional study in which a semistructured questionnaire which included an
open-ended question to assess theirmain concerns regarding TB in workplace was used to collect data. Results. Out of 305 resident
doctors approached, 263 (94%) completed a structured questionnaire and 200 of these responded to an open-ended question. Daily
exposure to TB was reported by 141 (64%) residents, 13 (5%) reported a prior history of TB, and 175 (69%) respondents were aware
of TB infection control guidelines. A majority reported concerns about acquiring TB (78%) and drug-resistant TB (88%).The key
themes identified were concerns about developing drug-resistant TB (𝑛 = 100; 50%); disease and its clinical consequences (𝑛 = 39;
20%); social and professional consequences (𝑛 = 37; 19%); exposure to TB patients (𝑛 = 32; 16%); poor infection control measures
(𝑛 = 27; 14%); and highworkload and its health consequences (𝑛 = 16; 8%). Conclusion.Though many resident doctors were aware
of TB infection control guidelines, only few expressed concern about lack of TB infection control measures. Doctors need to be
convinced of the importance of these measures which should be implemented urgently.
Objectives: The coronavirus disease 2019 pandemic has reinforced the use of personal protective equipments in healthcare settings. Although filtering face piece 2 respirators provide adequate protection from the aerosolised viral spread, their prolonged use is often associated with subjective discomfort. The study aimed to identify whether an intervening mask-free period is less harmful in terms of discomfort and desaturation when compared against continuous use for 6-h.
Material and Methods: This was a prospective and interventional study. A cohort of 87 previously healthy nurses from a multidisciplinary tertiary care hospital were recruited. Study participants were subjected to continuous and intermittent (with 15 min break) mask use, each for a 2-month duration, during their 6-h clinical shifts. Baseline and post-shift oxygen saturation (SpO2) were compared in real time using cumulative sum (CUSUM) statistics. Comfort level was also assessed on a scale of 0–10 in the two groups with 10 subjective parameters.
Results: Nurses have experienced a significant drop in SpO2 in both phases with 525 and 984 recordings in continuous and intermittent mask group, respectively. The mean % (2SD) saturation drop in the two groups was 4.688 (39.35) and 1.169 (2.62). The overall discomfort level was more in the continuous phase (8.89 ± 1.610) than
in intermittent (7.28 ± 3.216) mask use. CUSUM statistics helped in the real-time monitoring of subjects in the intermittent mask group.
Conclusions: Significant adverse health effects in healthcare workers are highlighted using objective and subjective parameters such as desaturation and discomfort levels while using protective face masks. A mask-free period of 15 min, in between their duty shifts, might help reduce the unfavourable effects without compromising efficacy.
Keywords: Coronavirus disease, Nurses, Cumulative sum, Oxygen saturation, Comfort score
The COVID-19 pandemic has affected the world and caused a supply shortage of personal protection equipment, especially filtering facepiece respirators (FFP). This has increased the risk of many healthcare workers of contracting SARS-CoV-2. Various strategies have been assessed to tackle these supply issues. In critical shortage scenarios, reusing of single-use-designed respirators may be required. Thus, an easily applicable and reliable FFP2 (or alike) respirator decontamination method, allowing safe re-use of FFP2 respirators by healthcare personnel, has been developed and is presented in this study. A potent and gentle aerosolized hydrogen peroxide (12% wt) method was applied over four hours to decontaminate various brands of FFP2 respirators within a small common room, followed by adequate aeration and storage overnight. The microbial efficacy was tested on unused respirator pieces using spores of Geobacillus stearothermophilus. Further, decontamination effectiveness was tested on used respirators after one 12-hour shift by swabbing before and after the decontamination. Effects of up to ten decontamination cycles on the respirators' functionality were evaluated by means of material properties, structural integrity of the respirators, and fit tests with subjects. The suggested H2O2 decontamination procedure was proven to be a) sufficiently potent (no microbial recovery, total inactivation of biological indicators as well as spore inoculum on critical respirator surfaces), b) gentle as no significant damage of the respirator structural integrity and acceptable fit factors were observed, c) safe as no H2O2 residue were detected after the defined aeration and storage. Thus, this easy-to-implement and scalable method could overcome another severe respirator-shortage, providing enough flexibility to draft safe, effective, and logistically simple crisis plans. However, as highlighted in this study, due to the wealth of design and material used in different models and brands of respirators, the decontamination process should be validated for each FFP respirator model before its field implementation.
Wearing a mask for a long time, particularly N95, is sometimes uncomfortable, annoying, and confining, making catching breath difficult and reducing the oxygen level in the blood. The study aimed to investigate the change in blood oxygen level when wearing an N95 mask for three hours among dental practitioners in dental clinics and the impact of low O2 levels on the general status of students while working in a stressful environment. Material and methods. The sample included 82 adult healthy senior dental students attending the student oral surgery clinical sessions. All Participants had their oxygen saturation Spo2 measured using a portable pulse oximeter before, 1hour, 2hours, and 3 hours after wearing the mask, and were allowed to describe their feeling of discomfort throughout the study. Systolic and diastolic blood pressure (SBP and DBP), and heart rate (HR) were also measured before and 3 hours after wearing the mask. Results. 84.15% (n= 69) of the participants reported some discomfort affecting their general status and clinical performance. There was a statistically significant increase in mean heart rate after three hours (P-value = 0.001) while there was no statistically significant change in mean systolic/diastolic blood pressure after three hours (P-value = 0.630) and (P-value=0.407) respectively. On the other hand, the mean Oxygen saturation after three hours showed a statistically significantly lower value compared with baseline measurement. Conclusion. This study revealed a decrease in the oxygen saturation (SpO2) and a slight increase in pulse rate compared to baseline values in all students three hours after wearing an N95 face mask. In addition, the N95 mask induced discomfort in breathing, a decrease in physical performance, and increased fatigue not related to prolonged standing and stress.
Amaç: Yüz maskelerinin rahatsız edici etkileri psikolojik etkinin ötesinde olabilir ve sağlık personelinin sağlığını tehlikeye atabilir. Bu çalışmada, 4 ve 8 saatlik vardiyalı cerrahi yüz maskesi ile çalışan sağlık personelinde maskeye bağlı psikolojik ve fizyolojik değişiklikleri saptamaktır. Yöntem: Çalışma, Ocak-Mart 2021 tarihleri arasında 102 sağlık çalışanı ile üçüncü basamak bir hastanede gerçekleştirildi. Kalp/akciğer hastalığı olan veya halen sigara içen kişiler çalışma dışı bırakıldı. Katılımcıların vücut ısısı, solunum/kalp hızı, kan basıncı, parmak ucu oksijen doygunluğu (SpO2) ölçümleri ve maske-rahatsızlık anketi vardiya başında, ortasında ve sonunda yapıldı. Bulgular: Araştırmaya katılan 102 gönüllünün 63'ü (%61,8) kadın olup, yaş ortalaması 30,92 ± 6,38'dir. En rahatsız edici maske rahatsızlığı, vardiya ortasında direnç ve vardiya sonunda yorgunluktu. Anketteki tüm parametrelerin puanları hem vardiya ortasında hem de vardiya sonunda başlangıca göre anlamlı olarak daha yüksekti (tüm parametreler için p=0,000). Vardiya sonunda nem, direnç, sıcaklık, tuzluluk, koku ve yorgunluk puanlarında vardiya ortasına göre anlamlı artışlar vardı (p=0,001, p=0,023, p=0,024, p=0,022, p=0,013 ve p
A COVID-19 consolidou-se como a principal pandemia dos últimos cem anos, tornando-se a principal causa de morte no Brasil e no mundo. Os sistemas de saúde, bem como as fontes de financiamento de pesquisas científicas voltaram seus holofotes para desenvolver estratégias de prevenção da disseminação do vírus Sars-Cov 2 e tratamento da COVID-19. Nesse cenário, o uso de máscaras para prevenir o contágio foi uma das principais estratégias adotadas pelos governos e sistemas de saúde. Apesar de estudos comprovarem a eficácia dessa metodologia para prevenir a infecção por vírus respiratórios, a segurança do seu uso não foi amplamente testada na população, de forma que grupos de risco não foram identificados. Assim, esse artigo se propõe a discutir a segurança do uso de máscaras pelas pessoas com epilepsia, que comprovadamente apresentam propensão a sofrer crises quando submetidos a alterações da fisiologia respiratória.
Español (see English below):
En este informe compilatorio se puede acceder a información científica y experimental sobre los efectos del uso permanente de mascarillas en la salud, con especial atención a las edades escolares. //
English:
This compilation report provides access to scientific and experimental information on the effects of regular use of facemasks on health, with a special focus on school-age children.
Covid-19 due to Sars-Cov-2 infection has reached pandemic proportion. Many healthcare workers are involved in managing both COVID-suspected and confirmed cases. It is mandatory for healthcare workers to have droplet and contact precautions by means of Personal protective equipment (PPE), facemask, face shield or eye protection. Prolonged usage of medical mask results in various adverse effects. This study is an attempt to know the common effects of prolonged face mask in healthcare workers and its resultant quality-of-life (QOL). To study the common effects of prolonged face mask and its impact on QOL of healthcare workers during the COVID 19 crisis. This was a prospective cross-sectional study conducted over 6 months among 2750 healthcare workers. A questionnaire requesting demographic details and most common side effects after prolonged usage of face mask was circulated. We also attached a short form-12 (sf-12) questionnaire to assess its impact on QOL. Out of 2750 personnel, 299 were excluded. Male preponderance was noted. Study was conducted on candidates using 3ply mask or above. Age range was between 18 and 65 years with mean age being 37.61 ± 15.23 in mask users < 5 h per day, 32.2 ± 10.02 in 5–10 h group and 30.19 ± 8.15 in 10 h group. 8.48% (n = 174) had comorbidities. QOL impacted. The complaints with face mask use definitely are troublesome with increase in severity with duration of mask usage. This definitely has a proportional impact on the healthcare workers’ QOL.
This study evaluated the effect of exhaled moisture on the breathing resistance of three classes of filtering facepiece respirators
(FFR) following 4 h of continuous wear at a breathing volume of 40 l min−1, utilizing an automated breathing and metabolic simulator as a human surrogate. After 4 h, inhalation and exhalation resistance
increased by 0.43 and 0.23 mm of H2O pressure, respectively, and average moisture retention in the respirators was 0.26 ml. Under ambient conditions similar
to those of the current study, and at similar breathing volumes, it is unlikely that exhaled moisture will add significantly
to the breathing resistance of filtering facepiece respirators (FFR) over 4 h of use.
Filtering facepiece respirators ('N95 Masks') may be in short supply during large-scale infectious outbreaks. Suggestions have been made to extend their useful life by using a surgical mask as an outer barrier, but the physiological impact of this added barrier upon the wearer has not been studied.
A surgical mask was worn over an N95 filtering facepiece respirator by 10 healthcare workers for 1 h at each of two work rates. Heart rate, respiratory rate, tidal volume, minute volume, oxygen saturation, transcutaneous carbon dioxide levels and respirator dead space gases were monitored and compared with controls (N95 filtering facepiece respirator without a surgical mask). Subjective perceptions of exertion and comfort were assessed by numerical rating scales.
There were no significant differences in physiological variables between those who used surgical masks and controls. Surgical masks decreased dead space oxygen concentrations of the filtering facepiece respirators at the lesser work rate (P = 0.03) and for filtering facepiece respirators with an exhalation valve at the higher work rate (P = 0.003). Respirator dead space oxygen and carbon dioxide levels were not harmonious with Occupational Safety and Health Administration workplace ambient atmosphere standards. Exertion and comfort scores were not significantly impacted by the surgical mask.
Use of a surgical mask as an outer barrier over N95 filtering facepiece respirators does not significantly impact the physiological burden or perceptions of comfort and exertion by the wearer over that experienced without use of a surgical mask.
Data about the effectiveness of the surgical mask compared with the N95 respirator for protecting health care workers against influenza are sparse. Given the likelihood that N95 respirators will be in short supply during a pandemic and not available in many countries, knowing the effectiveness of the surgical mask is of public health importance.
To compare the surgical mask with the N95 respirator in protecting health care workers against influenza.
Noninferiority randomized controlled trial of 446 nurses in emergency departments, medical units, and pediatric units in 8 tertiary care Ontario hospitals.
Assignment to either a fit-tested N95 respirator or a surgical mask when providing care to patients with febrile respiratory illness during the 2008-2009 influenza season.
The primary outcome was laboratory-confirmed influenza measured by polymerase chain reaction or a 4-fold rise in hemagglutinin titers. Effectiveness of the surgical mask was assessed as noninferiority of the surgical mask compared with the N95 respirator. The criterion for noninferiority was met if the lower limit of the 95% confidence interval (CI) for the reduction in incidence (N95 respirator minus surgical group) was greater than -9%.
Between September 23, 2008, and December 8, 2008, 478 nurses were assessed for eligibility and 446 nurses were enrolled and randomly assigned the intervention; 225 were allocated to receive surgical masks and 221 to N95 respirators. Influenza infection occurred in 50 nurses (23.6%) in the surgical mask group and in 48 (22.9%) in the N95 respirator group (absolute risk difference, -0.73%; 95% CI, -8.8% to 7.3%; P = .86), the lower confidence limit being inside the noninferiority limit of -9%.
Among nurses in Ontario tertiary care hospitals, use of a surgical mask compared with an N95 respirator resulted in noninferior rates of laboratory-confirmed influenza.
clinicaltrials.gov Identifier: NCT00756574
Few data are available about the effectiveness of nonpharmaceutical interventions for preventing influenza virus transmission.
To investigate whether hand hygiene and use of facemasks prevents household transmission of influenza.
Cluster randomized, controlled trial. Randomization was computer generated; allocation was concealed from treating physicians and clinics and implemented by study nurses at the time of the initial household visit. Participants and personnel administering the interventions were not blinded to group assignment. (ClinicalTrials.gov registration number: NCT00425893)
Households in Hong Kong.
407 people presenting to outpatient clinics with influenza-like illness who were positive for influenza A or B virus by rapid testing (index patients) and 794 household members (contacts) in 259 households.
Lifestyle education (control) (134 households), hand hygiene (136 households), or surgical facemasks plus hand hygiene (137 households) for all household members.
Influenza virus infection in contacts, as confirmed by reverse-transcription polymerase chain reaction (RT-PCR) or diagnosed clinically after 7 days.
Sixty (8%) contacts in the 259 households had RT-PCR-confirmed influenza virus infection in the 7 days after intervention. Hand hygiene with or without facemasks seemed to reduce influenza transmission, but the differences compared with the control group were not significant. In 154 households in which interventions were implemented within 36 hours of symptom onset in the index patient, transmission of RT-PCR-confirmed infection seemed reduced, an effect attributable to fewer infections among participants using facemasks plus hand hygiene (adjusted odds ratio, 0.33 [95% CI, 0.13 to 0.87]). Adherence to interventions varied.
The delay from index patient symptom onset to intervention and variable adherence may have mitigated intervention effectiveness.
Hand hygiene and facemasks seemed to prevent household transmission of influenza virus when implemented within 36 hours of index patient symptom onset. These findings suggest that nonpharmaceutical interventions are important for mitigation of pandemic and interpandemic influenza.
Centers for Disease Control and Prevention.
In the United States, two commonly used qualitative respirator fit test methods require the use of a test hood to be placed over the subject's head and shoulders. Workers fit tested by this method have commented on the discomfort of being inside the test hood. This study was designed to quantify some parameters that might lead to these types of comments. For this study, subjects performed a series of four respirator fit tests. A quantitative and a qualitative fit test were performed with a full facepiece respirator. Then a quantitative and a qualitative fit test were performed with an N95 filtering facepiece respirator. Parameters measured include: subjects’ height, weight, and age, oxygen and carbon dioxide levels, air temperature, heart rate, arterial oxygen saturation, and Borg Ratio Scale value on breathing exertion. Carbon dioxide levels are significantly higher and oxygen levels are significantly lower in the respirator when the test hood is used during the qualitative fit test. This was especially true when fit testing filtering facepieces where mean carbon dioxide levels rose to 4.2% and mean oxygen levels dropped to 15.5%. Full facepiece respirators had similar changes, but to a lesser magnitude. The temperature inside the test hood rose an average 7.5 °F in the course of the qualitative fit test of the N95 filtering facepiece device. These stressors are not present to such an extent during a quantitative respirator fit test. Professionals conducting respirator fit tests should be aware of the physiological burdens that may occur during the qualitative respirator fit test. Some groups may be especially sensitive to this test such as the elderly, pregnant women, persons with pulmonary and/or cardiac disease, or persons with psychological disorders such as anxiety, panic disorders, or claustrophobia.
Clinical question:
Are surgical masks inferior to N95 respirators in reducing influenza infection in health care workers?
Article chosen:
Loeb M, Dafoe N, Mahony J, et al. Surgical mask vs N95 respirator for preventing influenza among health care workers: a randomized trial. JAMA 2009;302:1865-71.
Objective:
To evaluate the effectiveness of N95 respirators compared to standard surgical masks in reducing influenza infection in health care workers.
We compared the efficacy of medical masks, N95 respirators (fit tested and non fit tested), in health care workers (HCWs).
A cluster randomized clinical trial (RCT) of 1441 HCWs in 15 Beijing hospitals was performed during the 2008/2009 winter. Participants wore masks or respirators during the entire work shift for 4 weeks. Outcomes included clinical respiratory illness (CRI), influenza-like illness (ILI), laboratory-confirmed respiratory virus infection and influenza. A convenience no-mask/respirator group of 481 health workers from nine hospitals was compared.
The rates of CRI (3·9% versus 6·7%), ILI (0·3% versus 0·6%), laboratory-confirmed respiratory virus (1·4% versus 2·6%) and influenza (0·3% versus 1%) infection were consistently lower for the N95 group compared to medical masks. By intention-to-treat analysis, when P values were adjusted for clustering, non-fit-tested N95 respirators were significantly more protective than medical masks against CRI, but no other outcomes were significant. The rates of all outcomes were higher in the convenience no-mask group compared to the intervention arms. There was no significant difference in outcomes between the N95 arms with and without fit testing. Rates of fit test failure were low. In a post hoc analysis adjusted for potential confounders, N95 masks and hospital level were significant, but medical masks, vaccination, handwashing and high-risk procedures were not.
Rates of infection in the medical mask group were double that in the N95 group. A benefit of respirators is suggested but would need to be confirmed by a larger trial, as this study may have been underpowered. The finding on fit testing is specific to the type of respirator used in the study and cannot be generalized to other respirators.
Australian New Zealand Clinical Trials Registry (ANZCTR), ACTRN: ACTRN12609000257268 (http://www.anzctr.org.au).
To the Editor: Dr Loeb and colleagues1 reported that use of surgical masks compared with N95 respirators among nurses resulted in noninferior rates of laboratory-confirmed influenza. However, their conclusion that the 2 devices offer similar respiratory protection may be inaccurate. The reported influenza rates reflect much more than efficacy of the devices evaluated. Hence, altering clinical practice based on the study's conclusions may expose health care workers and patients to unnecessary risks.
To the Editor: The study by Dr Loeb and colleagues1 concluded, “Among nurses in Ontario tertiary care hospitals, use of a surgical mask compared with an N95 respirator resulted in noninferior rates of laboratory-confirmed influenza.” However, the study methods did not describe the filtering efficiency of the surgical masks that were used in this study.A study by Oberg and Brosseau2 noted that “surgical masks vary widely in style and intended application” and stated that the Food and Drug Administration recommends that surgical masks be rated using the criteria of particulate filtration efficiency and bacterial filtration efficiency. Masks labeled as surgical masks have a wide range of efficiencies and a range of leakage around the periphery of the mask, depending on its fit on the face. The filtering efficiencies of the masks that were used in the study by Loeb et al are relevant to the study results since surgical masks available in other institutions may not have the same efficiencies for particulates and bacteria, or the same fit.
To the Editor: I believe that the study by Dr Loeb and colleagues1 was not sufficiently powered to support their hypothesis that the surgical mask offers protection similar to the N95 respirator among health care workers exposed to influenza. The authors stated that the 20% event rate required to adequately power the study was achieved. However, this would only be accurate had the nurses worn the assigned masks for the entire study period (not solely when caring for isolated patients). Data from the Centers for Disease Control and Prevention (CDC)2 and serologic studies, including one cited by the authors,3 suggest that more than 50% of the events (influenza transmissions) likely occurred when nurses were wearing no mask. These events are not usable when deciding to refute or accept the authors' hypothesis. The issue is not whether these “no-mask” transmissions (presumably exposures to nonisolated patients, sick health care workers, or community and household contacts) were evenly distributed between the 2 experimental groups. Instead, these no-mask events cannot be used to power the study because the experimental conditions were not in place.
We assessed the effect of dry air (DA) nasal breathing on nasal clearance rate in healthy nonsmoking subjects. We measured saccharin nasal transit time (SNTT), an index of mucociliary clearance rate, in eleven normal subjects (six males, five females) breathing either room air (RA) or DA through the nose in random order on six different study days. On each study day, the trial was conducted at the same time, in the same nostril, using a patent airway. DA was breathed through a light-weight, tight-fitting, nasal mask (SEFAM, France) for 30 min and SNTT was then measured immediately. Saccharin (250 micrograms) was deposited on the anterior part of the inferior turbinate under visual control and saliva was swallowed every 30 s thereafter. SNTT was the time elapsed between deposition and first perception of saccharin taste. The group-average SNTT on DA was 18.5 +/- 8.6 min which was significantly longer than on RA (11.9 +/- 5.3 min). Our findings suggest that dry air breathing results in excessive water loss by the nasal mucosa, which may in turn reduce nasal mucociliary clearance rate through changes in the rheological properties or adhesiveness of nasal mucus and/or slowing of ciliary beating.
To review the available literature on the relationship between the humidity and temperature of inspired gas and airway mucosal function.
International computerized databases and published indices, experts in the field, conference proceedings, bibliographies.
Two hundred articles/texts on respiratory tract physiology and humidification were reviewed. Seventeen articles were selected from 40 articles for inclusion in the published data verification of the model. Selection was by independent reviewers. Extraction was by consensus, and was based on finding sufficient data.
A relationship exists between inspired gas humidity and temperature, exposure time to a given humidity level, and mucosal function. This relationship can be modeled and represented as an inspired humidity magnitude vs. exposure time map. The model is predictive of mucosal function and can be partially verified by the available literature. It predicts that if inspired humidity deviates from an optimal level, a progressive mucosal dysfunction begins. The greater the humidity deviation, the faster the mucosal dysfunction progresses.
A model for the relationship between airway mucosal dysfunction and the combination of the humidity of inspired gas and the duration over which the airway mucosa is exposed to that humidity is proposed. This model suggests that there is an optimal temperature and humidity above which, and below which, there is impaired mucosal function. This optimal level of temperature and humidity is core temperature and 100% relative humidity. However, existing data are only sufficient to test this model for gas conditions below core temperature and 100% relative humidity. These data concur with the model in that region. No studies have yet looked at this relationship beyond 24 hrs. Longer exposure times to any given level of inspired humidity and inspired gas temperatures and humidities above core temperature and 100% relative humidity need to be studied to fully verify the proposed model.
The study was aimed at investigating the effects of wearing N95 and surgical facemasks with and without nano-functional treatments on thermophysiological responses and the subjective perception of discomfort.
Five healthy male and five healthy female participants performed intermittent exercise on a treadmill while wearing the protective facemasks in a climate chamber controlled at an air temperature of 25 degrees C and a relative humidity of 70%. Four types of facemasks, including N95 (3M 8210) and surgical facemasks, which were treated with nano-functional materials, were used in the study.
(1) The subjects had significantly lower average heart rates when wearing nano-treated and untreated surgical facemasks than when wearing nano-treated and untreated N95 facemasks. (2) The outer surface temperature of both surgical facemasks was significantly higher than that of both N95 facemasks. On the other hand, the microclimate and skin temperatures inside the facemask were significantly lower than those in both N95 facemasks. (3) Both surgical facemasks had significantly higher absolute humidity outside the surface than both N95 facemasks. The absolute humidity inside the surgical facemask was significantly lower than that inside both N95 facemasks. (4) Both surgical facemasks were rated significantly lower for perception of humidity, heat, breath resistance and overall discomfort than both N95 facemasks. The ratings for other sensations, including feeling unfit, tight, itchy, fatigued, odorous and salty, that were obtained while the subjects were wearing the surgical facemasks were significantly lower than when the subjects were wearing the N95 facemasks. (5) Subjective preference for the nano-treated surgical facemasks was the highest. There was significant differences in preference between the nano-treated and untreated surgical facemasks and between the surgical and N95 facemasks.
We discuss how N95 and surgical facemasks induce significantly different temperature and humidity in the microclimates of the facemasks, which have profound influences on heart rate and thermal stress and subjective perception of discomfort.
During the 2003 severe acute respiratory distress syndrome epidemic, healthcare workers mandatorily wore the protective N95 face-mask.
We administered a survey to healthcare workers to determine risk factors associated with development of headaches (frequency, headache subtypes and duration of face-mask wear) and the impact of headaches (sick days, headache frequency and use of abortive/preventive headache medications).
In the survey, 212 (47 male, 165 female) healthcare workers of mean age 31 years (range, 21-58) participated. Of the 79 (37.3%) respondents who reported face-mask-associated headaches, 26 (32.9%) reported headache frequency exceeding six times per month. Six (7.6%) had taken sick leave from March 2003 to June 2004 (mean 2 days; range 1-4 days) and 47 (59.5%) required use of abortive analgesics because of headache. Four (2.1%) took preventive medications for headaches during this period. Multivariate logistic regression showed that pre-existing headaches [P = 0.041, OR = 1.97 (95% CI 1.03-3.77)] and continuous use of the N95 face-mask exceeding 4 h [P = 0.053, OR = 1.85 (95% CI 0.99-3.43)] were associated with development of headaches.
Healthcare providers may develop headaches following the use of the N95 face-mask. Shorter duration of face-mask wear may reduce the frequency and severity of these headaches.
Respiratory protection devices are used to protect the wearers from inhaling particles suspended in the air. Filtering face piece respirators are usually tested utilizing nonbiologic particles, whereas their use often aims at reducing exposure to biologic aerosols, including infectious agents such as viruses and bacteria.
The performance of 2 types of N95 half-mask, filtering face piece respirators and 2 types of surgical masks were determined. The collection efficiency of these respiratory protection devices was investigated using MS2 virus (a nonharmful simulant of several pathogens). The virions were detected in the particle size range of 10 to 80 nm.
The results indicate that the penetration of virions through the National Institute for Occupational Safety and Health (NIOSH)-certified N95 respirators can exceed an expected level of 5%. As anticipated, the tested surgical masks showed a much higher particle penetration because they are known to be less efficient than the N95 respirators. The 2 surgical masks, which originated from the same manufacturer, showed tremendously different penetration levels of the MS2 virions: 20.5% and 84.5%, respectively, at an inhalation flow rate of 85 L/min.
The N95 filtering face piece respirators may not provide the expected protection level against small virions. Some surgical masks may let a significant fraction of airborne viruses penetrate through their filters, providing very low protection against aerosolized infectious agents in the size range of 10 to 80 nm. It should be noted that the surgical masks are primarily designed to protect the environment from the wearer, whereas the respirators are supposed to protect the wearer from the environment.
The SARS outbreak in 2003 has spawned a major controversy concerning protective performance facemasks for healthcare workers. This study reports a study on in-vivo protective performance of surgical masks and N95 respirators.
Typical surgical masks and N95 respirators used in Hong Kong hospitals were tested in comparison with those treated with nano-functional materials (called nano-masks) on various physical properties and in-vivo wear filtration efficiency, as well as usability test in hospitals for surgical masks.
Tests on physical properties showed that N95 respirators had significantly lower air permeability and water vapor permeability than surgical masks. The in-vivo filtration tests illustrated that N95 respirators filtered out 97% of potassium chloride (KCl) solution, while surgical masks filtered out 95% of KCl solution. Nano-masks show stronger water repellency and antibacterial activities, but no difference in usability, comparing with normal N95 and surgical masks.
Surgical masks can provide in-vivo filtration protection of 95% filtration efficiency. N95 respirators provide higher in-vivo filtration efficiency of 97% with significant reduction of air permeability and water vapor permeability. Compared to normal surgical masks/respirators, the nano-masks can provide additional protective functions in stopping capillary diffusion and antibacterial activities.
Surgical masks have been used since the early 1900s to minimize infection of surgical wounds from wearer-generated bacteria. There is ongoing debate, however, whether surgical masks can meet the expectations of respiratory protection devices. The goal of this study was to evaluate the filter performance and facial fit of a sample of surgical masks.
Filter penetration was measured for at least 3 replicates of 9 surgical masks using monodisperse latex sphere aerosols (0.895, 2.0, and 3.1 microm) at 6 L/min and 0.075-microm sodium chloride particles at 84 L/min. Facial fit was measured on 20 subjects for the 5 masks with lowest particle penetration, using both qualitative and quantitative fit tests.
Masks typically used in dental settings collected particles with significantly lower efficiency than those typically used in hospital settings. All subjects failed the unassisted qualitative fit test on the first exercise (normal breathing). Eighteen subjects failed the assisted qualitative fit tests; 60% failed on the first exercise. Quantitative fit factors ranged from 2.5 to 9.6.
None of these surgical masks exhibited adequate filter performance and facial fit characteristics to be considered respiratory protection devices.
Objective assessment of increase in breathing resistance of N95 respirators on human subjects
- Lee Hp
- D Y Wang