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1.
Sci Rep ; 11(1): 24490, 2021 12 29.
Article in English | MEDLINE | ID: covidwho-1594104

ABSTRACT

During the first wave of Covid-19 infections in Germany in April 2020, clinics reported a shortage of filtering face masks with aerosol retention> 94% (FFP2 & 3, KN95, N95). Companies all over the world increased their production capacities, but quality control of once-certified materials and masks came up short. To help identify falsely labeled masks and ensure safe protection equipment, we tested 101 different batches of masks in 993 measurements with a self-made setup based on DIN standards. An aerosol generator provided a NaCl test aerosol which was applied to the mask. A laser aerosol spectrometer measured the aerosol concentration in a range from 90 to 500 nm to quantify the masks' retention. Of 101 tested mask batches, only 31 batches kept what their label promised. Especially in the initial phase of the pandemic in Germany, we observed fluctuating mask qualities. Many batches show very high variability in aerosol retention. In addition, by measuring with a laser aerosol spectrometer, we were able to show that not all masks filter small and large particles equally well. In this study we demonstrate how important internal and independent quality controls are, especially in times of need and shortage of personal protection equipment.


Subject(s)
COVID-19/prevention & control , COVID-19/transmission , Masks/statistics & numerical data , Aerosols , Filtration/instrumentation , Germany , Humans , Masks/standards , Masks/trends , N95 Respirators/standards , N95 Respirators/statistics & numerical data , Occupational Exposure/prevention & control , Pandemics/prevention & control , Personal Protective Equipment/standards , Quality Control , Respiratory Protective Devices/standards , SARS-CoV-2/pathogenicity
2.
Rural Remote Health ; 21(3): 6596, 2021 07.
Article in English | MEDLINE | ID: covidwho-1579427

ABSTRACT

INTRODUCTION: Face masks are widely recommended as a COVID-19 prevention strategy. State mask mandates have generally reduced the spread of the disease, but decisions to wear a mask depend on many factors. Recent increases in case rates in rural areas following initial outbreaks in more densely populated areas highlight the need to focus on prevention and education. Messaging about disease risk has faced challenges in rural areas in the past. While surges in cases within some communities are likely an impetus for behavior change, rising case rates likely explain only part of mask-wearing decisions. The current study examined the relationship between county-level indicators of rurality and mask wearing in the USA. METHODS: National data from the New York Times' COVID-19 cross-sectional mask survey was used to identify the percentage of a county's residents who reported always/frequently wearing a mask (2-14 July 2020). The New York Times' COVID-19 data repository was used to calculate county-level daily case rates for the 2 weeks preceding the mask survey (15 June - 1 July 2020), and defined county rurality using the Index of Relative Rurality (n=3103 counties). Multivariate linear regression was used to predict mask wearing across levels of rurality. The model was adjusted for daily case rates and other relevant county-level confounders, including county-level indicators of age, race/ethnicity, gender, political partisanship, income inequality, and whether each county was subject to a statewide mask mandate. RESULTS: Large clusters of counties with high rurality and low mask wearing were observed in the Midwest, upper Midwest, and mountainous West. Holding daily case rates and other county characteristics constant, the predicted probability of wearing a mask decreased significantly as counties became more rural (β=-0.560; p<0.0001). CONCLUSION: Upticks in COVID-19 cases and deaths in rural areas are expected to continue, and localized outbreaks will likely occur indefinitely. The present findings highlight the need to better understand the mechanisms underlying perceptions of COVID-19 risk in rural areas. Dissemination of scientifically correct and consistent information is critical during national emergencies.


Subject(s)
COVID-19/epidemiology , COVID-19/prevention & control , Health Status Disparities , Masks/trends , Rural Population/trends , Cross-Sectional Studies , Female , Humans , Linear Models , Male , Severity of Illness Index , Socioeconomic Factors
3.
Sci Rep ; 11(1): 21675, 2021 11 04.
Article in English | MEDLINE | ID: covidwho-1504246

ABSTRACT

The recent outbreak of the COVID-19 led to death of millions of people worldwide. To stave off the spread of the virus, the authorities in the US employed different strategies, including the mask mandate order issued by the states' governors. In the current work, we defined a parameter called average death ratio as the monthly average of the number of daily deaths to the monthly average number of daily cases. We utilized survey data to quantify people's abidance by the mask mandate order. Additionally, we implicitly addressed the extent to which people abide by the mask mandate order, which may depend on some parameters such as population, income, and education level. Using different machine learning classification algorithms, we investigated how the decrease or increase in death ratio for the counties in the US West Coast correlates with the input parameters. The results showed that for the majority of counties, the mask mandate order decreased the death ratio, reflecting the effectiveness of such a preventive measure on the West Coast. Additionally, the changes in the death ratio demonstrated a noticeable correlation with the socio-economic condition of each county. Moreover, the results showed a promising classification accuracy score as high as 90%.


Subject(s)
COVID-19/mortality , COVID-19/prevention & control , Masks/trends , California , Guideline Adherence/trends , Health Policy , Humans , Machine Learning , Masks/statistics & numerical data , Oregon , SARS-CoV-2/pathogenicity , Washington
4.
PLoS One ; 16(10): e0259037, 2021.
Article in English | MEDLINE | ID: covidwho-1496524

ABSTRACT

Epidemiological simulations as a method are used to better understand and predict the spreading of infectious diseases, for example of COVID-19. This paper presents an approach that combines a well-established approach from transportation modelling that uses person-centric data-driven human mobility modelling with a mechanistic infection model and a person-centric disease progression model. The model includes the consequences of different room sizes, air exchange rates, disease import, changed activity participation rates over time (coming from mobility data), masks, indoors vs. outdoors leisure activities, and of contact tracing. It is validated against the infection dynamics in Berlin (Germany). The model can be used to understand the contributions of different activity types to the infection dynamics over time. It predicts the effects of contact reductions, school closures/vacations, masks, or the effect of moving leisure activities from outdoors to indoors in fall, and is thus able to quantitatively predict the consequences of interventions. It is shown that these effects are best given as additive changes of the reproduction number R. The model also explains why contact reductions have decreasing marginal returns, i.e. the first 50% of contact reductions have considerably more effect than the second 50%. Our work shows that is is possible to build detailed epidemiological simulations from microscopic mobility models relatively quickly. They can be used to investigate mechanical aspects of the dynamics, such as the transmission from political decisions via human behavior to infections, consequences of different lockdown measures, or consequences of wearing masks in certain situations. The results can be used to inform political decisions.


Subject(s)
COVID-19/prevention & control , Communicable Disease Control/methods , Contact Tracing/methods , Berlin , COVID-19/metabolism , Cell Phone/trends , Computer Simulation , Germany , Hand Disinfection/trends , Humans , Masks/trends , Models, Theoretical , Physical Distancing , Population Dynamics/trends , SARS-CoV-2/pathogenicity , Systems Analysis
6.
Neuron ; 109(12): 1918-1920, 2021 06 16.
Article in English | MEDLINE | ID: covidwho-1272636

ABSTRACT

Worldwide use of face masks as personal protective equipment (PPE) during the COVID-19 pandemic has changed interpersonal interactions in myriad ways, likely permanently. Creative strategies like the PPE Portrait Project serve to mitigate social disconnection resulting from facial feature obstruction.


Subject(s)
COVID-19/psychology , Facial Expression , Interpersonal Relations , Masks/trends , COVID-19/prevention & control , Expressed Emotion/physiology , Forecasting , Humans , Personal Protective Equipment/trends
7.
Proc Natl Acad Sci U S A ; 118(21)2021 05 25.
Article in English | MEDLINE | ID: covidwho-1219283

ABSTRACT

The tempo-spatial patterns of Covid-19 infections are a result of nested personal, societal, and political decisions that involve complicated epidemiological dynamics across overlapping spatial scales. High infection "hotspots" interspersed within regions where infections remained sporadic were ubiquitous early in the outbreak, but the spatial signature of the infection evolved to affect most regions equally, albeit with distinct temporal patterns. The sparseness of Covid-19 infections in the United States was analyzed at scales spanning from 10 to 2,600 km (county to continental scale). Spatial evolution of Covid-19 cases in the United States followed multifractal scaling. A rapid increase in the spatial correlation was identified early in the outbreak (March to April). Then, the increase continued at a slower rate and approached the spatial correlation of human population. Instead of adopting agent-based models that require tracking of individuals, a kernel-modulated approach is developed to characterize the dynamic spreading of disease in a multifractal distributed susceptible population. Multiphase Covid-19 epidemics were reasonably reproduced by the proposed kernel-modulated susceptible-infectious-recovered (SIR) model. The work explained the fact that while the reproduction number was reduced due to nonpharmaceutical interventions (e.g., masks, social distancing, etc.), subsequent multiple epidemic waves still occurred; this was due to an increase in susceptible population flow following a relaxation of travel restrictions and corollary stay-at-home orders. This study provides an original interpretation of Covid-19 spread together with a pragmatic approach that can be imminently used to capture the spatial intermittency at all epidemiologically relevant scales while preserving the "disordered" spatial pattern of infectious cases.


Subject(s)
COVID-19/epidemiology , COVID-19/transmission , COVID-19/metabolism , Humans , Masks/trends , Models, Theoretical , Pandemics , Physical Distancing , SARS-CoV-2/isolation & purification , United States/epidemiology
8.
Ann Ig ; 33(4): 347-359, 2021.
Article in English | MEDLINE | ID: covidwho-1207913

ABSTRACT

Background: Health authorities and organizations consider non-medical face masks as an additional passive means to prevent virus diffusion. Communication strategies disseminate information among the population that such masks are essential for mitigating virus diffusion. However, scientific studies are not conclusive in showing the undisputed filtration efficiency of fabric/cloth facial masks (both commercial and homemade). Objectives: This study examines scientific data about the effectiveness of face masks before and during the COVID-19 emergency. Present trends in the making of commercial and homemade fabric/cloth face masks are also examined. Methods: Statistical data of published studies are analyzed and compared. Main considerations and sugge-stions are also extracted and discussed. Current approaches are examined for assessing the characteristics and effectiveness of fabric/cloth commercial and homemade face masks intended for the population. Results: Conflicting data exist as to whether non-medical masks have a protective effect from the spread of respiratory viruses. Both medical masks (MDs) and respiratory personal protection equipment (PPE) show a given effectiveness value. Conclusion: Concerning commercial and homemade fabric/cloth masks, giving general indications on the choice of materials and their assemblage is difficult as it is not possible to assess the effectiveness of the filter media with respect to the kind of multiphase fluid that may be emitted upon breathing, sneezing, or coughing under different environmental conditions. This is particularly important because airflow rate, temperature, humidity, and duration of use will affect the performance of filter media. Moreover, while a mask may have excellent filter media, droplets may leak into the face-piece unless there is an adequate facial seal. In the presence of leaks, any type of mask may actually offer less protection independently of its nominal filtering effìciency.


Subject(s)
COVID-19/prevention & control , Masks , SARS-CoV-2 , Aerosols , Air Microbiology , Cough , Equipment Design , Evaluation Studies as Topic , Filtration , Humans , Humidity , Masks/standards , Masks/trends , Polypropylenes , Respiration , SARS-CoV-2/isolation & purification , Sneezing , Temperature , Textiles
9.
PLoS One ; 16(4): e0250817, 2021.
Article in English | MEDLINE | ID: covidwho-1206206

ABSTRACT

The coronavirus disease 2019 (COVID-19) has caused an unprecedented public health crisis worldwide. Its intense politicization constantly made headlines, especially regarding the use of face masks as a safety precaution. However, the extent to which public opinion is polarized on wearing masks has remained anecdotal and the verbal representation of this polarization has not been explored. This study examined the types, themes, temporal trends, and exchange patterns of hashtags about mask wearing posted from March 1 to August 1, 2020 by Twitter users based in the United States. On the one hand, we found a stark rhetorical polarization in terms of semantic antagonism between pro- and anti-mask hashtags, exponential frequency increases of both types of hashtags during the period under study, in parallel to growing COVID-19 case counts, state mask mandates, and media coverage. On the other hand, the results showed an asymmetric participatory polarization in terms of a predominance of pro-mask hashtags along with an "echo chamber" effect in the dominant pro-mask group, which ignored the subversive rhetoric of the anti-mask minority. Notwithstanding the limitations of the research, this study provides a nuanced account of the digital polarization of public opinion on mask wearing. It draws attention to political polarization both as a rhetorical phenomenon and as a participatory process.


Subject(s)
COVID-19/psychology , Masks/trends , Social Media/trends , Humans , Pandemics/prevention & control , Politics , Public Health , SARS-CoV-2/pathogenicity , United States/epidemiology
10.
A A Pract ; 15(4): e01449, 2021 Apr 27.
Article in English | MEDLINE | ID: covidwho-1204121

ABSTRACT

Snorkel masks have become an option for personal protective equipment (PPE) due to the shortage of air filtration at least 95% of airborne particle (N95) masks as a result of the coronavirus disease 2019 (COVID-19) pandemic. We developed a 3D design of a triheaded adapter that connects a snorkel mask to 3 different National Institute for Occupational Safety and Health (NIOSH)-approved air filtration at least 99% of airborne particles (N99) filters with the aim of improving wearer comfort. We measured the resistance of the new triheaded adapter to be one-third the resistance of the single adapter. Interdepartmental survey of anesthesiologists showed an improvement in perceived comfort when using the triheaded adapter as compared to the single adapter.


Subject(s)
Anesthesiologists/trends , COVID-19/prevention & control , Equipment Design/trends , Masks/trends , Occupational Exposure/prevention & control , Personal Protective Equipment/trends , Anesthesiologists/standards , COVID-19/epidemiology , Equipment Design/standards , Humans , Masks/standards , Personal Protective Equipment/standards
11.
PLoS One ; 16(4): e0249677, 2021.
Article in English | MEDLINE | ID: covidwho-1194500

ABSTRACT

The COVID-19 pandemic has caused severe health and economic impacts globally. Strategies to safely reopen economies, travel and trade are a high priority. Until a reliable vaccine is available, non-pharmaceutical techniques are the only available means of disease control. In this paper, we aim to evaluate the extent to which social distancing (SD) and facemask (FM) use can mitigate the transmission of COVID-19 when restrictions are lifted. We used a microsimulation activity-based model for Sydney Greater Metropolitan Area, to evaluate the power of SD and FM in controlling the pandemic under numerous scenarios. The hypothetical scenarios are designed to picture feasible futures under different assumptions. Assuming that the isolation of infected cases and the quarantining of close contacts are in place, different numerical tests are conducted and a full factorial two-way MANOVA test is used to evaluate the effectiveness of the FM and SD control strategies. The main and interactive effects of the containment strategies are evaluated by the total number of infections, percentage of infections reduction, the time it takes to get the pandemic under control, and the intensity of active cases.


Subject(s)
COVID-19/economics , COVID-19/prevention & control , Masks/economics , Masks/trends , Physical Distancing , Humans , Models, Theoretical , Pandemics/prevention & control , Quarantine , SARS-CoV-2/isolation & purification , Travel
12.
PLoS One ; 16(3): e0248272, 2021.
Article in English | MEDLINE | ID: covidwho-1150539

ABSTRACT

INTRODUCTION: Coronavirus disease-2019 (COVID-19) is a highly contagious acute respiratory disease, which caused by a novel coronavirus. The disease disrupts health systems and resulting in social, political, and economic crises. Health professionals are in front of this pandemic and always work in a high-risk environment. The best prevention for COVID-19 is avoiding exposure to the virus. Some studies reported health professional's practice of precautionary measures for COVID-19. Nevertheless, a few have identified factors affecting. As such, this study aimed to fill those research gaps in the study setting. METHODS: In this cross-sectional study, 428 health professionals involved from the public health facilities of the Gamo zone, southern Ethiopia. A simple random sampling method employed, and the data collected by the interviewer-administered Open Data Kit survey tool and observational checklist. The data analyzed in Stata version 15, and a binary logistic regression model used to identify factors. In this study, a statistically significant association declared at P< 0.05. RESULTS: In this study, 35.3% (95%CI: 30.7%, 39.8%) of health professionals' had a good practice on precautionary measures for the COVID-19 pandemic. Use hand sanitizer or wash hands continuously with soap and water (68.9%), cover nose and mouth with a tissue during sneezing or coughing (67.3%), and use facemask in crowds (56.8%) were the most common practice reported by study participants. Marital status, being married (AOR = 1.84, 95%CI: 1.06, 3.18), good knowledge on the COVID-19 pandemic (AOR = 2.02, 95%CI: 1.02, 3.18), and positive attitude towards precautionary measures for the COVID-19 were factors showed significant association with the practice. CONCLUSIONS: The magnitude of good practice of precautionary measures for the COVID-19 pandemic among health professionals was low. As such, different interventions to improve the knowledge and attitude of health professionals in the health care system are highly needed to boost the practice and to advance service delivery.


Subject(s)
COVID-19/psychology , Health Personnel/psychology , Personal Protective Equipment/trends , Adult , COVID-19/epidemiology , Cross-Sectional Studies , Ethiopia/epidemiology , Female , Health Facilities , Health Knowledge, Attitudes, Practice , Humans , Knowledge , Male , Masks/trends , Pandemics/prevention & control , SARS-CoV-2/pathogenicity , Surveys and Questionnaires
13.
PLoS One ; 16(3): e0248706, 2021.
Article in English | MEDLINE | ID: covidwho-1148246

ABSTRACT

BACKGROUND: The world is grappling with an ever-changing COVID-19 pandemic using preventive measures such as personal hygiene, face masks, restrictions on travel and gatherings in communities, in addition to a race to find a vaccine. The purpose of this study was to evaluate the knowledge, attitudes and practices of the western Uganda community on the proper use of face masks to mitigate the spread of COVID-19. METHODS: A cross-sectional study using a structured questionnaire was carried out from 1st July to 10th July 2020 among western Ugandans of consent age of 18 years and above. Data was analysed using Stata version 14.2. RESULTS: Among the respondents (n = 1114), the mean age was 30.7 (SD 11.1), 51% were males, 53.9% married and 43% had attained secondary education. Most participants (60.1%, n = 670) had satisfactory knowledge on the use of face masks and participants at a tertiary education level [AOR 2.6 (95% CI: 1.42-4.67; p = 0.002)] were likely to have satisfactory knowledge than participants who had not education. On attitude, most respondents (69.4%) were confident enough to correctly put on a face mask; 83.4% believed that a face mask can protect against COVID-19 and 75.9% of respondents had never shared their face mask. The majority of respondents (95.2%) agreed wearing face masks in public places was important to protect themselves against COVID-19; 60.3% reported washing their hands before wearing and after removing the face mask. Unfortunately, 51.5% reported removing the face mask if they needed to talk to someone. CONCLUSION: Despite the satisfactory knowledge, good attitude and practices, there is still much more to be done in terms of knowledge, attitude and practices among participants. Government, non-governmental organizations and civil society should improve sensitization of populations on how to behave with face masks while talking to avoid the spread of the COVID-19 among western Ugandans.


Subject(s)
COVID-19/prevention & control , Masks/statistics & numerical data , Masks/trends , Adolescent , Adult , Aged , Aged, 80 and over , COVID-19/transmission , Cross-Sectional Studies , Female , Health Knowledge, Attitudes, Practice/ethnology , Humans , Knowledge , Male , Masks/virology , Middle Aged , Pandemics/prevention & control , SARS-CoV-2/pathogenicity , Surveys and Questionnaires , Uganda/epidemiology
14.
Am J Public Health ; 111(5): 937-948, 2021 05.
Article in English | MEDLINE | ID: covidwho-1140578

ABSTRACT

Objectives. To examine how sociodemographic, political, religious, and civic characteristics; trust in science; and fixed versus fluid worldview were associated with evolving public support for social distancing, indoor mask wearing, and contact tracing to control the COVID-19 pandemic.Methods. Surveys were conducted with a nationally representative cohort of US adults in April, July, and November 2020.Results. Support for social distancing among US adults dropped from 89% in April to 79% in July, but then remained stable in November 2020 at 78%. In July and November, more than three quarters of respondents supported mask wearing and nearly as many supported contact tracing. In regression-adjusted models, support differences for social distancing, mask wearing, and contact tracing were most pronounced by age, partisanship, and trust in science. Having a more fluid worldview independently predicted higher support for contact tracing.Conclusions. Ongoing resistance to nonpharmaceutical public health responses among key subgroups challenge transmission control.Public Health Implications. Developing persuasive communication efforts targeting young adults, political conservatives, and those distrusting science should be a critical priority.


Subject(s)
COVID-19/prevention & control , Contact Tracing , Masks/trends , Physical Distancing , Public Health/trends , Adult , Aged , Contact Tracing/statistics & numerical data , Contact Tracing/trends , Female , Humans , Male , Middle Aged , Politics , Science , Socioeconomic Factors , Surveys and Questionnaires
15.
Int J Psychol ; 56(4): 607-622, 2021 Aug.
Article in English | MEDLINE | ID: covidwho-1136986

ABSTRACT

Nonpharmaceutical interventions (NPI) such as stay-at-home orders aim at curbing the spread of the novel coronavirus, SARS-COV-2. In March 2020, a large proportion of the German population supported such interventions. In this article, we analyse whether the support for NPI dwindle with economic worries superimposing virus-related worries in the months to follow. We test seven pre-registered1 hypotheses using data from the German COSMO survey (Betsch, Wieler, Habersaat, et al. 2020), which regularly monitors behavioural and psychological factors related to the pandemic. The present article covers the period from March 24, 2020 to July 7, 2020 (Ntotal  = 13,094), and, in addition, includes a validation study providing evidence for the reliability and validity of the corresponding COSMO measures (N = 612). Results revealed that virus-related worries decreased over time, whereas economic worries remained largely constant. Moreover, the acceptance of NPIs considerably decreased over time. Virus-related worries were positively associated with acceptance of NPIs, whereas this relationship was negative regarding economic worries (albeit smaller and less consistent). Unexpectedly, no interactions between virus-related worries and economic worries were found. We conclude that individual differences in virus-related and economic threat perceptions related to COVID-19 play an important role in the acceptance of NPIs.


Subject(s)
COVID-19/economics , COVID-19/psychology , Patient Acceptance of Health Care/psychology , Socioeconomic Factors , Surveys and Questionnaires , Adolescent , Adult , Aged , Aged, 80 and over , Anxiety/economics , Anxiety/epidemiology , Anxiety/psychology , Anxiety/therapy , COVID-19/epidemiology , COVID-19/therapy , Female , Germany/epidemiology , Humans , Male , Masks/economics , Masks/trends , Middle Aged , Prospective Studies , Reproducibility of Results , Young Adult
17.
Sci Rep ; 11(1): 5577, 2021 03 10.
Article in English | MEDLINE | ID: covidwho-1125020

ABSTRACT

Covid-19 pandemics has fostered a pervasive use of facemasks all around the world. While they help in preventing infection, there are concerns related to the possible impact of facemasks on social communication. The present study investigates how emotion recognition, trust attribution and re-identification of faces differ when faces are seen without mask, with a standard medical facemask, and with a transparent facemask restoring visual access to the mouth region. Our results show that, in contrast to standard medical facemasks, transparent masks significantly spare the capability to recognize emotional expressions. Moreover, transparent masks spare the capability to infer trustworthiness from faces with respect to standard medical facemasks which, in turn, dampen the perceived untrustworthiness of faces. Remarkably, while transparent masks (unlike standard masks) do not impair emotion recognition and trust attribution, they seemingly do impair the subsequent re-identification of the same, unmasked, face (like standard masks). Taken together, this evidence supports a dissociation between mechanisms sustaining emotion and identity processing. This study represents a pivotal step in the much-needed analysis of face reading when the lower portion of the face is occluded by a facemask.


Subject(s)
COVID-19/psychology , Masks/adverse effects , Trust/psychology , Adult , Communication , Emotions/physiology , Face , Facial Recognition/physiology , Female , Humans , Internet , Italy , Male , Masks/trends , SARS-CoV-2/pathogenicity , Social Perception/psychology , Surveys and Questionnaires
18.
PLoS One ; 16(3): e0248099, 2021.
Article in English | MEDLINE | ID: covidwho-1115311

ABSTRACT

Since the appearance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the question regarding the efficacy of various hygiene measures and the use of personal protective equipment (PPE) has become the focus of scientific and above all public discussion. To compare respirators, medical face masks, and cloth masks and determine if it is recommendable to wear face masks to protect the individual wearer of the mask from inhaling airborne particles, we challenged 29 different masks with aerosols and tested the pressure drop as a surrogate for breathing resistance owing to the mask material. We found that Type II medical face masks showed the lowest pressure drop (12.9±6.8 Pa/cm2) and therefore additional breathing resistance, whereas respirators such as the KN95 (32.3±7.0 Pa/cm2) and FFP2 (26.8±7.4 Pa/cm2) showed the highest pressure drops among the tested masks. The filtration efficacy of the mask material was the lowest for cloth masks (28±25%) followed by non-certified face masks (63±19%) and certified medical face masks (70±10%). The materials of the different respirators showed very high aerosol retentions (KN95 [94±4%] and FFP2 [98±1%]). For evaluating the as-worn filtration performance simulating real live conditions each mask type was also tested on a standardized dummy head. Cloth masks and non-EN-certified face masks had the worst as-worn filtration efficacies among the tested masks, filtering less than 20% of the test aerosol. Remarkably, certified type II medical face masks showed similar (p>0.5) as-worn filtration results (47±20%) than KN95 masks (41±4%) and FFP2 masks (65±27%), despite having a lower pressure drop. Face shields did not show any significant retention function against aerosols in our experiment. Our results indicate that it seems recommendable to wear face masks for providing base protection and risk reduction against inhaling airborne particles, in low-risk situations. In our study, especially EN 14683 type II certified medical face masks showed protective effectiveness against aerosols accompanied by minimal additional breathing resistance. FFP2 Respirators, on the other hand, could be useful in high-risk situations but require greater breathing effort and therefore physical stress for users.


Subject(s)
COVID-19/transmission , Disease Transmission, Infectious/prevention & control , Masks/trends , Aerosols , COVID-19/epidemiology , Filtration , Humans , Models, Statistical , Occupational Exposure/prevention & control , Personal Protective Equipment/trends , Respiratory Protective Devices/virology , SARS-CoV-2/pathogenicity
19.
PLoS One ; 16(2): e0246720, 2021.
Article in English | MEDLINE | ID: covidwho-1088757

ABSTRACT

Filtering facepiece respirators (FFRs) and medical masks are widely used to reduce the inhalation exposure of airborne particulates and biohazardous aerosols. Their protective capacity largely depends on the fraction of these that are filtered from the incoming air volume. While the performance and physics of different filter materials have been the topic of intensive study, less well understood are the effects of mask sealing. To address this, we introduce an approach to calculate the influence of face-seal leakage on filtration ratio and fit factor based on an analytical model and a finite element method (FEM) model, both of which take into account time-dependent human respiration velocities. Using these, we calculate the filtration ratio and fit factor for a range of ventilation resistance values relevant to filter materials, 500-2500 Pa∙s∙m-1, where the filtration ratio and fit factor are calculated as a function of the mask gap dimensions, with good agreement between analytical and numerical models. The results show that the filtration ratio and fit factor are decrease markedly with even small increases in gap area. We also calculate particle filtration rates for N95 FFRs with various ventilation resistances and two commercial FFRs exemplars. Taken together, this work underscores the critical importance of forming a tight seal around the face as a factor in mask performance, where our straightforward analytical model can be readily applied to obtain estimates of mask performance.


Subject(s)
Filtration/methods , Respiratory Protective Devices/statistics & numerical data , Aerosols/analysis , Air Filters , Equipment Design , Finite Element Analysis , Humans , Inhalation Exposure/analysis , Masks/statistics & numerical data , Masks/trends , Materials Testing/methods , Models, Theoretical , N95 Respirators/statistics & numerical data , Particle Size , Respiration , Respiratory Protective Devices/standards , Ventilators, Mechanical/statistics & numerical data , Ventilators, Mechanical/trends
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