scholarly journals Filtration efficiency of face masks and veils as protective measures during COVID-19 pandemic

2021 ◽  
Author(s):  
Khaled S. Al-Hadyan ◽  
◽  
Ghazi A. Alsbeih Alsbeih ◽  
Najla M. Al-Harbi ◽  
Sara S. Bin Judia ◽  
...  
Keyword(s):  
Particle Size ◽  
Control Measure ◽  
Filtration Efficiency ◽  
Experimental Conditions ◽  
Surgical Masks ◽  
Significant Difference ◽  
Comparable Performance ◽  
The Face ◽  
3D Printed ◽  
The Mean

Wearing face masks have been implemented as a public and personal health control measure against the spread of coronavirus disease (COVID-19). However, the protection level of nonmedical face masks, such as women face veils, is still uncertain. This study aimed to assess the filtration efficiency (FE; percentage of particles retained by a mask) of different types of medical masks (either as sealed or unsealed, single or doubled), non-medical masks (cloth masks) and face veils. FE of face masks was evaluated using an in-house 3D-printed air duct connected to the Aerotrak particle counter with a capability of counting particle sizes of 0.3, 0.5, 0.7, 1, 2 and 5 μm. A set of 10 earloop surgical masks,10 tie-on surgical masks, 3 triple-layers reusable cloth masks and 3 types (short, medium and long) of traditional face veils were included in the study. The unsealed surgical masks showed intermediate FE (36.54-80.58%), with no observed differences between tie-on and earloop or single and doubled masks. For each mask type, the mean FE values of sealed surgical masks (FE≥99.16%) was significantly higher (P<0.001) than the unsealed ones (FE≤80.58%). No significant difference was observed in the mean FE values between unsealed surgical masks and either cloth masks (FE=23.19-75.35%, P=0.26) or face veils (FE=19.10- 70.68%, P=0.14). However, a mockup experiment showed that wearing a surgical mask under the face veil significantly improve the FE (33.73-79.18%; P<0.001). We conclude that besides sealed surgical masks that ensure optimal filtration under the experimental conditions, the unsealed surgical and cloth masks and face veils showed comparable performance and acceptable protection at 5 μm particle size, which is the most relevant particle size associated with COVID-19 infectious droplets. Wearing a surgical mask under the face veil significantly improves the FE compared to wearing a face veil alone.

scholarly journals Particle Size-Selective Assessment of Protection of European Standard FFP Respirators and Surgical Masks against Particles-Tested with Human Subjects

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Shu-An Lee ◽  
Dong-Chir Hwang ◽  
He-Yi Li ◽  
Chieh-Fu Tsai ◽  
Chun-Wan Chen ◽  
...  
Keyword(s):  
Particle Size ◽  
Human Subjects ◽  
Strong Association ◽  
European Standard ◽  
Sampling System ◽  
Protection Level ◽  
British Standard ◽  
Surgical Masks ◽  
Significant Difference ◽  
Personal Sampling

This study was conducted to investigate the protection of disposable filtering half-facepiece respirators of different grades against particles between 0.093 and 1.61 μm. A personal sampling system was used to particle size-selectively assess the protection of respirators. The results show that about 10.9% of FFP2 respirators and 28.2% of FFP3 respirators demonstrate assigned protection factors (APFs) below 10 and 20, which are the levels assigned for these respirators by the British Standard. On average, the protection factors of FFP respirators were 11.5 to 15.9 times greater than those of surgical masks. The minimum protection factors (PFs) were observed for particles between 0.263 and 0.384 μm. No significant difference in PF results was found among FFP respirator categories and particle size. A strong association between fit factors and protection factors was found. The study indicates that FFP respirators may not achieve the expected protection level and the APFs may need to be revised for these classes of respirators.

scholarly journals A novel method using 3D CBCT to assess anterior malar prominence among native Bangalore population- A descriptive study

2021 ◽  
Vol 7 (3) ◽  
pp. 223-228
Author(s):  
Sanda Aamani ◽  
Hemanth M ◽  
Sharmada B K ◽  
Karthik J Kabbur ◽  
Goutham Kalladka
Keyword(s):  
Descriptive Study ◽  
T Test ◽  
Linear Measurements ◽  
Mean Values ◽  
Significant Difference ◽  
The Face ◽  
Novel Method ◽  
Males And Females ◽  
The Mean ◽  
Paired T Test

There is a lack of accurate three-dimensional studies to locate malar prominence for specified population, this study aims to locate the malar prominence using stable landmarks using CBCT. To derive a novel method to accurately locate the malar prominence and to assess and compare the malar prominence between males and females among Bangalore population using 3D CBCT study. All CBCT scans of study subjects belong to Bangalore population were collected from the pre-existing data available in Radiology imaging Solutions (CBCT centre), Bangalore during the period of September 10th to October 10th 2020. This is a descriptive study. A total of 42 subjects including 21 Males and 21 females were assessed using full skull CBCT scans which were converted to DICOM format and reconstructed into 3D images using NEMOCEPH 3D software. Landmarks used to locate the malar prominence were Fzs, Z, Zm and Ans. The intersection of these landmarks is considered to be as constructed maxillozygion(My). For the accuracy of the constructed Maxillozygion point (My), the distance between the actual Maxillozygion (Mzy) and constructed Maxillozygion (My) is measured and calculated between left and right halves of males and females. Three Orthogonal planes constructed were Midsagittal, Axial and Coronal Planes and the linear measurements with reference to all three reference planes in both the groups are measured. Student paired t- Test, Independent Student t Test, Mann Whitney Test. The mean distance from Mzy and my between right and left half of the face was compared using student paired t- Test. There is no significant difference (p=0.35).The mean values of the constructed anatomical landmark (maxillozygion) coordinated to three orthogonal planes between right and left sides of the face is compared using student paired T test and for both the genders (males and females) was compared using Independent Student t Test, and it is significantly higher in males as compared to females and it is statistically significant at (p=0.01). The location of malar prominence using CBCT by a novel method for Bangalore population is found which can be helpful in diagnosis and treatment planning for malar augmentation, camouflage treatment in subjects with midface deficiencies.

The Filtration Efficiency of Single-Layer Textiles for Respiratory protection

2021 ◽  
Vol 3 (2) ◽  
pp. 1-12
Author(s):  
Behnam Pourdeyhimi ◽  
Simon Schick ◽  
Robert Groten
Keyword(s):  
Particle Size ◽  
Single Layer ◽  
Face Mask ◽  
Filtration Efficiency ◽  
Respiratory Protection ◽  
Test Protocol ◽  
Astm Standard ◽  
The Face

Due to the increasing number of corona cases and the face mask industry's associated bottleneck, this work focuses on the various single-layer textiles used as cloth masks. The purpose of this work is to test ten different single-layer textiles for their suitability as face masks. All tests in this work were carried out based on the ASTM F2299 and the new ASTM Standard for barrier masks (3502-21). The new standard offers a more precisely defined test protocol and is consistent with how respirators are tested. The results show that only one of the ten textiles tested meets the ASTM requirements for a barrier mask. We also include data for ASTM F2299 and report the results for unneutralized challenge particles at various face velocities for the same single-layer textiles. These results are different from those of the ASTM 3502 because the particle size and the procedure used are different.  Under ASTM 3502, the resistance values ​​are significantly higher, and the efficiency values ​​are significantly lower than those reported by using the ASTM F2299.

scholarly journals Surgical Hand Antisepsis With Alcohol-Based Hand Rub Comparison of Effectiveness After 1.5 and 3 Minutes of Application

2009 ◽  
Vol 30 (5) ◽  
pp. 420-426 ◽  
Author(s):  
Walter P. Weber ◽  
Stefan Reck ◽  
Uschi Neff ◽  
Ramon Saccilotto ◽  
Marc Dangel ◽  
...  
Keyword(s):  
University Hospital ◽  
Bacterial Reduction ◽  
Experimental Conditions ◽  
Postdoctoral Training ◽  
Sustained Effect ◽  
Colony Forming Units ◽  
Significant Difference ◽  
Hand Antisepsis ◽  
European Norm ◽  
The Mean

Objective.Research has shown 1.5 minutes of surgical hand antisepsis with alcohol-based hand rub to be at least as effective under experimental conditions as the 3-minute reference disinfection recommended by European Norm 12791. The aim of the present study was to validate the effectiveness of 1.5 minutes of surgical hand antisepsis in a clinical setting by comparing the effectiveness of 1.5- and 3-minute applications of alcohol-based hand rub (45% vol/vol 2-propanol, 30% vol/vol 1-propanol, and 0.2% mecetronium ethylsulphate).Design.Prospective crossover trial in which each surgeon served as his or her own control, with individual randomization to the 1.5-or the 3-minute group during the first part of the trial.Setting.Basel University Hospital, Switzerland.Participants.Thirty-two surgeons with different levels of postdoctoral training.Methods.We measured the bactericidal effectiveness of 1.5 minutes and 3 minutes of surgical hand antisepsis with alcohol-based hand rub by assessing the mean (± SD) log10 number of colony-forming units before the application of hand rub (baseline), after the application of hand rub (immediate effect), and after surgery (sustained effect) so as to follow European Norm 12791 as closely as possible.Results.The immediate mean (± SD) log10 reduction in colony-forming units (cfu) was 2.66 ±1.13 log10 cfu for the 1.5-minute group and 3.01 ±1.06 log10 cfu for the 3-minute group (P = .204). Similarly, there was no statistically significant difference between the 2 groups with respect to the sustained effect; the mean ( ± SD) log10 increase in bacterial density during surgery was 1.08 ± 1.13 log10 cfu for the 1.5-minute group and 0.95 ± 1.27 log10 cfu for the 3-minute group (P = .708). No adverse effects were recorded.Conclusion.In this clinical trial, surgical hand antisepsis with alcohol-based hand rub resulted in a similar bacterial reduction, regardless of whether it was applied for 3 or 1.5 minutes, which confirms experimental data generated with healthy volunteers.

scholarly journals Is the Current N95 Respirator Filtration Efficiency Test Sufficient for Evaluating Protection Against Submicrometer Particles Containing SARS-CoV-2?

2020 ◽  
Author(s):  
Changjie Cai ◽  
Evan L. Floyd ◽  
Kathleen A. Aithinne ◽  
Toluwanimi Oni
Keyword(s):  
Particle Size ◽  
Sodium Chloride ◽  
Occupational Safety ◽  
Filtration Efficiency ◽  
Geometric Standard Deviation ◽  
Negative Effects ◽  
Significant Difference ◽  
Median Diameter ◽  
Efficiency Test ◽  
20 Nm

AbstractThe National Institute of Occupational Safety and Health procedure No. TEB-APR-STP-0059 recommend of measuring the respirator filtration efficiency using sodium chloride aerosol with count median diameter of 75 nm ± 20 nm and geometric standard deviation ≤1.86. This study showed that this method would overestimate the respirators’ ability to protect against submicrometer particles. In this study, we converted both mobility diameter and equivalent volume diameter to aerodynamic diameter for comparison. The results showed that one unqualified KN95 respirator (with the filtration efficiency of 72%±3% for ≥300 nm sodium chloride aerosol) still passed the test with a measured overall filtration efficiency of 98%±3%, due to its larger most penetrating particle size compared to the typical N95 respirator. In addition, after three cycle H2O2 plasma vaporous sterilizations, the most penetrating particle size for the N95 grade respirators also shifted to 250 nm – 500 nm, in which size the particles carried the peak concentration of the SARS-CoV-2 in hospitals. This size shift caused the significant difference between the size specific (250 nm – 500 nm) filtration efficiency and overall filtration efficiency using the same NaCl test aerosol. For example, after three cycle H2O2 plasma vaporous sterilizations, the size specific filtration efficiency of the N95 was 55%±2%, however, the measured overall filtration efficiency was still 86%±5%. The size Specific filtration efficiency of the KN95 was 69%±2%, but, the measured overall filtration efficiency was still 90%±3%. In order to protect health care personnel adequately, we recommend increasing the test aerosol size, and measuring the size specific filtration efficiency to evaluate the N95 alternatives (e.g. KN95), and the reuse of N95 level respirators. In addition, multi-cycle sterilization with ultraviolet germicidal irradiation appears to have fewer negative effects than H2O2.

scholarly journals A Customized Mask Retainer and Its Effects on Improving the Fit Performance of Surgical Masks

2021 ◽  
Author(s):  
Xi Chen ◽  
Qi Xi ◽  
Wei Lu ◽  
Fangfang Sun ◽  
Lirong Wang ◽  
...  
Keyword(s):  
Fold Increase ◽  
Face Mask ◽  
Matched Pairs ◽  
3D Face ◽  
Surgical Masks ◽  
The Face ◽  
3D Printed ◽  
Scan Data ◽  
N95 Respirators ◽  
Chinese Standard

Abstract Background: With the outbreak of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the effectiveness of providing mask protection is important for people. This article introduces a customized mask retainer to improve the fit performance of face masks.Methods: The participant’s 3D face scans with and without a surgical mask were taken by using a 3D face scanner. The fitter was designed on the 3D face scan data according to the facial anthropometric landmarks, and examined and adjusted on the face scan data with a mask. The fitter was 3D printed using a metal printer for Titanium. The effectiveness of the fitter on augmentation of fit of surgical mask was test according to the Chinese Standard. Tests were repeated three times per participant, and compare differences between groups by Wilcoxon Matched-Pairs Signed-Ranks Test using software (a=.05).Results: The effectiveness test of the retainer on augmentation of fit performance showed a result more than 25-fold increase of overall Fit Factor, which have met the fit requirement for KN95 respirators in China.Conclusions: Fit Factor results indicated that by using the retainer, the Fit Factors of overall and each exercise have significantly increased as compared to that of face mask alone group. It may provide a solution to the shortage of N95 respirators the world is now encountering as fighting against the COVID-19 epidemic.

scholarly journals 577-nm high-power optically pumped semiconductor laser is safe and effective in the treatment of inflammatory acne: a prospective, single-center, split-face comparative study

2021 ◽  
Vol 26 (1) ◽  
Author(s):  
E. M. Mohamed ◽  
K. M. Tawfik ◽  
I. B. Elsayed ◽  
E. Bölke ◽  
P. A. Gerber
Keyword(s):  
Semiconductor Laser ◽  
High Power ◽  
Acne Vulgaris ◽  
Optically Pumped ◽  
Control Side ◽  
Significant Difference ◽  
The Face ◽  
The Mean ◽  
Split Face ◽  
Single Lesion

Abstract Objective This study aimed to appraise the efficacy of a 577-nm high-power optically pumped semiconductor laser (HOPSL) for the treatment of inflammatory acne. Methods The study included 50 patients with acne vulgaris (inflammatory type), 14 men, and 36 women; patient ages ranged from 16 to 35 years. The left side of the face was treated with a single pass of a 577-nm high-power optically pumped semiconductor laser (HOPSL) every 2 weeks for 3 sessions. The severity of acne examined prior to the first session and 4 weeks after the last session (Investigator's Global Assessment of acne severity, IGA; single lesion count). Results At baseline, no statistically significant difference in the severity of inflammatory acne lesions between both sides was observed. One month after the final session, a significant improvement (IGA reduction of > 50%) of the overall severity of acne was observed in 49 patients (98%) on the laser-treated side versus 41 (82%) the control side of the face (P < .05). Hence, we found a significant reduction in the mean percentage of inflammatory papules, pustules, and nodules on the laser-treated versus the control side (79.33 vs 56.92, 78.04 vs 43.33, 64.85 vs 21.93%, respectively) (P < 0.05). Side effects in the form of erythema and irritation during sessions were transient and tolerated by the patients. Conclusion The 577-nm high-power optically pumped semiconductor laser is effective and safe for the treatment of inflammatory lesions (papules, pustules, and nodules) in acne patients.

The Effect of Silicol Gel Compared with Placebo on Papulopustular Acne and Sebum Production. A Double-Blind Study

1996 ◽  
Vol 24 (4) ◽  
pp. 340-344 ◽  
Author(s):  
A Lassus
Keyword(s):  
Placebo Group ◽  
Treated Group ◽  
Double Blind Study ◽  
Concomitant Treatment ◽  
Double Blind ◽  
Area 5 ◽  
Significant Difference ◽  
The Face ◽  
Sebum Production ◽  
The Mean

Altogether 30 patients (19 females and 11 males), mean age 19 years, were divided randomly into two groups. All patients had chronic papulopustular acne of the face. A total of 15 patients were treated topically with Silicol gel for 20 min twice daily for 6 weeks and the remaining 15 patients were treated with a placebo gel in a similar fashion. A clinical evaluation was carried out at baseline, and after 2, 4 and 6 weeks of treatment. The clinical variables evaluated were as follows: number of comedones, papules, pustules and cysts on a standard area of the left cheek (area 5 × 5 cm) and measurement of sebum production on the same area by the use of Sebumeter SM 810 PC (Courage and Khazaka, Ltd, Germany). No concomitant treatment was allowed during the study period. One patient using Silicol gel withdrew after 2 weeks of treatment because of severe irritation of the facial skin, leaving 29 patients who could be evaluated. In the active group, the number of comedones decreased from a mean of 48.5 to 15.1 after 6 weeks of treatment. The corresponding figures for papules were 10.7 and 1.0, for pustules 6.8 and 0, and for cysts 0.6 and 0. In the placebo group no improvement could be observed. There was a highly significant difference in efficacy between the two groups ( P < 0.001) in favour of the actively treated group. The mean sebum index was 193 at baseline and 88 after 6 weeks. Correspondingly, in the placebo group the mean sebum index at baseline was 187 and after 6 weeks 179. This difference between the two groups was also statistically significant ( P < 0.001). After a short follow-up period (3 months) no deterioration was observed in the 14 ‘active’ patients, showing either complete cure or improvement.

scholarly journals Effect of Face-to-Face and Multimedia Methods of Education on Children’s Constipation Severity

2021 ◽  
Vol 7 (4) ◽  
pp. 303-310
Author(s):  
Sajjad Pirooz-arjmandi ◽  
◽  
Mahbobeh Sajadi ◽  
Akram Bayati ◽  
Nooshin Sajadei ◽  
...  
Keyword(s):  
Functional Constipation ◽  
Training Group ◽  
Educational Interventions ◽  
T Test ◽  
Exact Test ◽  
Face To Face ◽  
Significant Difference ◽  
The Face ◽  
Constipation Severity ◽  
The Mean

Background: Constipation is a common problem among children. The aim of this study was to compare the effect of face-to-face and multimedia education on the severity of functional constipation in children. Methods: It was a two-group pre-test post-test quasi-experimental study that was carried out at the Specialized Clinics of Pediatrics affiliated with the Arak University of Medical Sciences, Arak, Iran. The sample consisted of 96 eligible children in the age range of 6 to 12 years that were randomly assigned to face-to-face (n=48) and multimedia (n=48) groups. Functional constipation was detected by Rome ΙΙΙ criteria. Data were collected by a demographic characteristics form and the Constipation Assessment Scale (CAS) before intervention and one month later in both groups. In the face-to-face group, education was provided using two 15-min training sessions in the form of a lecture in the presence of the mother. The multimedia training group received a 15-min training video. Both groups were given a pamphlet. The data were analyzed by Fisher’s exact test, independent t-test, and paired t-test using SPSS version 16. Results: There was no significant difference between the groups’ constipation severity before the intervention (P=0.12). There was a significant difference between the mean score of constipation severity between the face-to-face (P=0.01) and multimedia (P=0.001) groups before and after the intervention. However, the mean±SD score of constipation severity after the intervention was 7.05±1.79 in the face-to-face group and 5.91±1.69 in the multimedia group (p=0.001). Conclusion: The results of this study showed that both educational interventions reduced the severity of constipation in children. However, multimedia training was more effective than face-to-face education so that it reduced the severity of constipation to a greater extent.

scholarly journals Grain textural analysis across a range of glacial facies

1999 ◽  
Vol 28 ◽  
pp. 111-117 ◽  
Author(s):  
A. Khatwa ◽  
J. K. Hart ◽  
A. J. Payne
Keyword(s):  
Particle Size ◽  
Fractal Dimension ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Diagnostic Criteria ◽  
Fractal Dimensions ◽  
Textural Analysis ◽  
Significant Difference ◽  
The Mean

AbstractA technique proposed by Hooke and Iverson (1995) to identify deformed subglacial sediments is reviewed and tested, based on two main objectives. First, an investigation of whether the fractal dimension can distinguish between non-deformed and deformed facies; for which we compare supraglacial and subglacial facies explicitly. Second, an evaluation of whether the fractal dimension can be used as a diagnostic criteria to discriminate between different styles and degrees of basal deformation. This is tested using a range of sediments from the deformation continuum suggested by Hart and Boulton (1991b). Sixteen subglacial samples were selected from Quaternary sites in England and three supraglacial samples from the modern Haut Glacier d’Arolla, Switzerland. The mean fractal dimension for the subglacial diamicton matrix facies was 2.92, similar to findings of 2.90 by Hooke and Iverson (1995) for their basal tills. The supraglacial facies displayed a mean fractal dimension of 2.83, which is unusually high for facies which are assumed to be undeformed. A Mann—Whitney U test showed that fractal dimensions of supraglacial and subglacial diamicton matrix facies were not significantly different. No significant difference was found between the fractal dimensions of the different tectonic facies within the subglacial group. It may be impossible to separate the subglacial and supraglacial facies because of complex debris paths within the glacier. Grain fracture or parent lithology may affect the particle-size distribution of subglacial facies.

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