Comparison of the inward leakage rate between N95 filtering facepiece respirators and modified surgical masks during the COVID-19 pandemic

BACKGROUND@#Owing to shortage of surgical and N95 filtering facepiece respirators (FFRs) during the COVID-2019 pandemic, various masks were developed to prevent infection. This study aimed to examine the inward leakage rate (ILR) of sealed face masks and modified surgical masks using a quantitative fit test and compared it with the ILR of unmodified N95 FFRs.@*METHODS@#We conducted paired comparisons of ILRs of bent nose-fit wire masks, double masks, and N95 FFRs from October to December 2021. To measure the protective effectiveness of masks, participants wore masks, and the number of particles outside and inside the mask were measured. The ILR was based on the percentage of particles entering the mask using a fit tester.@*RESULTS@#We enrolled 54 participants (20 men and 34 women) in this study. The median ILR for surgical masks without and with a W-shaped bend in the nose-fit wire were 96.44% and 50.82%, respectively. The nose-fit wire adjustment reduced the ILR of surgical masks by a mean of 28.57%, which was significantly lower than the ILR without adjustment (P < 0.001). For double masks, with surgical or polyurethane masks on top of the W-shaped mask, the ILR did not differ significantly from that of N95. Although the filtration performance of double surgical masks matched that of N95 masks, their ILR was notably higher, indicating that double masks do not provide equivalent protection.@*CONCLUSIONS@#Wearing N95 masks alone is effective in many cases. However, surgical mask modifications do not guarantee consistent effectiveness. Properly selected, sealed masks with a good fit overcome leakage, emphasizing their crucial role. Without evidence, mask-wearing may lead to unexpected infections. Education based on quantitative data is crucial for preventing adverse outcomes.

How to use χ2 test correctly——χ2 distribution and the related contents / 四川精神卫生

The purpose of this article was to introduce the χ2 distribution and related contents， including χ2 distribution and non-central χ2 distribution. It focused on showing the definition of two χ2 distributions， the graph and the main properties of the probability density function. Among them， the two most important properties were： first， the limiting distribution of the χ2 distribution was the normal distribution； second， n-1s2σ2followed the χ2 distribution with n-1 degrees of freedom.In addition， it also explained the relationship between the χ2 distribution and the normal distribution， the relationship between χ2 test statistic and Z test statistic. Finally， it illustrated the computational approaches of the χ2 distribution based on the two SAS functions in SAS software.

How to use χ2 test correctly—— the goodness of fit tests and the implementation of the SAS software / 四川精神卫生

The purpose of this article was to introduce the goodness of fit test and its SAS implementation. The main contents included the following four aspects： ① Pearson΄s goodness of fit test； ② deviance or likelihood ratio goodness of fit test； ③ Hosmer-Lemeshow goodness of fit test； ④ goodness of fit test for the sparse data. In the aforementioned “fourth aspect”， there were six specific test approaches， namely “information matrix test” “information matrix diagonal test” “Osius-Rojek test” “unweighted residual sum of squares test” “Spiegelhalter test” and “Stukel test”. The paper implemented the four types of the goodness of fit tests mentioned above with the help of the SAS software through an example， explained the output results， and made statistical and professional conclusions.

Suitability survey on N95 filter masks for public health emergency personnel / 上海预防医学

Objective To assess the suitability of N95 masks for public health emergency personnel, and to compare the consistency between mask suitability test result and subjective evaluation of mask air tightness so as to guide scientific selection and use of protection masks for emergency personnel. Methods By ambient aerosol condensation nuclear counter method, qualitative suitability test was done among 235 public health emergency personnel from both municipal and district disease control centers.Questionnaires were conducted among them for investigation and comparison of their subjective evaluation of mask air tightness and mask suitability test results. Results Of the 235 subjects, 160 passed the suitability test with the pass rate being 68.1%. With various wearing actions for the test, the subjective evaluation for mask air tightness was compared with suitability test pass rate in terms of consistence, the kappa value range being from -0.09 to 0.43.The kappa value of the action 5 (loudly speaking) was above 0.4, while the kappa values of other 6 actions were all below 0.4.Both kappa value (0.09) and consistency rate (49.7%) were the lowest for action 8 (normal breathing) among all test actions. Conclusion The accuracy of the subjective evaluation for air tightness of the mask proves to be poor, unable to reflect the true protective effect and unable to substitute the suitability test.It is advised that the public health personnel should rely on the suitability test results to correctly choose and use suitable respiratory protective products.

Suitability survey on N95 filter masks for public health emergency personnel / 上海预防医学

Objective To assess the suitability of N95 masks for public health emergency personnel. To compare the consistency between mask fit test result and subjective evaluation of mask-wearing air tightness so as to guide scientific selection and use of protection masks for emergency personnel. Methods By ambient aerosol condensation nuclear counter method, the quantitative fit test was done among 235 public health emergency personnel from both Municipal and District disease control centers. Questionnaires were conducted among them for investigation and comparison of their subjective evaluation of mask-wearing air tightness and mask fit test results. Results Of the 235 subjects , 160 passed the fittest with the pass rate being 68.1%. With various wearing actions for the test, the subjective evaluation for mask-wearing air tightness was compared with the fit test pass rate in terms of consistence, the kappa value range being from −0.09 to 0.43. K value of the action 5 (loudly speaking) was above 0.4, while the k values of other 6 actions were all below 0.4. Both Kappa value (0.09) and consistency rate (49.7%) were the lowest for action 8 (normal breathing) among all test actions. Conclusion The accuracy of the subjective evaluation for mask-wearing air tightness proves to be poor, unable to reflect the true protective effect and substitute for the fit test. It is advised that the public health personnel should rely on the fit test results to correctly choose and use suitable respiratory protective products.

Outcomes Of Physical Fitness For Young Males With Type Ii Diabetes In Ksa

Background: Diabetes mellitus is one of the common public problems that its prevalence increase incredibly in the last three decades in KSA. The purpose of this work is to investigate the physical fitness of young male subjects with type 2 diabetes mellitus in KSA. Also, study the reliability of ALPHA-FIT test battery as easy, quick physical tools to test the physical fitness among Saudi society patients. Methods: Thirty males with type 2 diabetic were participated in the study and compared with thirty healthy volunteers represent the control group. The participants were investigated for their physical fitness by the ALPHA-FIT test battery. The seven categories of the test battery that forming the essential physical fitness for adults health and function. Results: The results of the study showed that there was a significant reduction in the physical fitness of the diabetic group compared with the control group. The cardiorespiratory fitness, the hand-grip is showing muscular strength, jump-to-reach indicating lower limbs power and strength, modified push-up owing to the trunk and upper limbs muscular endurance, standing on one-leg referring to balance state all results showing p-value < 0.05. In comparing both groups, there were no significant differences between diabetic and control groups regarding body mass index and waist circumference measures p-value > 0.05. Conclusion: Musculoskeletal and cardiorespiratory fitness were significantly lowered in patients with diabetes compared to age matching people. Health awareness and early physical intervention are recommended to prevent this reduction of fitness.

Investigation and Analysis of Familial Aggregation of Helicobacter pylori Infection / 胃肠病学

Background: Helicobacter pylori (Hp) infection is an important public health problem, and the transmission mode of Hp is not yet fully understood, however, human-to-human transmission route has been widely recognized, thus familial aggregation may occur for Hp infection. Aims: To explore the Hp infection in family members of Hp-positive patients and to analyze the familial aggregation of Hp infection. Methods: A total of 976 patients who underwent 14C-urea breath test (14C-UBT) from January 2018 to January 2019 were enrolled. According to Hp infection, the subjects were divided into Hp-positive group (case group) and Hp-negative group (control group), and all family members of all the subjects were encouraged to detect Hp infection. The Hp infection of family members in the two groups, the consistence of Hp infection between husband and wife, and the relationship between Hp-positive parents and Hp infection of children in case group were analyzed, and the goodness-of-fit test for binomial distribution was used to explore familial aggregation of Hp infection. Results: Among the 493 complete families who completed the survey, Hp-positivity rate in parents, spouses, children in case group were 70.6%, 62.1%, 65.9%, respectively, and were significantly higher than those in parents, spouses, children in control group (63.2%, 54.4%, 56.7%, respectively) (P0.05). Among 548 children in case group, 361 children were Hp positive, and the infection rate was increased with the increase of parental infection (P<0.05). The goodness-of-fit test showed that there were statistically significant differences in the actual households distribution and theoretical households distribution of Hp infection (P<0.05). Conclusions: There is a certain familial aggregation of Hp infection. When a member of the family is infected, the risk of Hp infection of parents, spouses and children may increase.

Survival analysis: part II – applied clinical data analysis / 대한마취과학회지

As a follow-up to a previous article, this review provides several in-depth concepts regarding a survival analysis. Also, several codes for specific survival analysis are listed to enhance the understanding of such an analysis and to provide an applicable survival analysis method. A proportional hazard assumption is an important concept in survival analysis. Validation of this assumption is crucial for survival analysis. For this purpose, a graphical analysis method and a goodness-of-fit test are introduced along with detailed codes and examples. In the case of a violated proportional hazard assumption, the extended models of a Cox regression are required. Simplified concepts of a stratified Cox proportional hazard model and time-dependent Cox regression are also described. The source code for an actual analysis using an available statistical package with a detailed interpretation of the results can enable the realization of survival analysis with personal data. To enhance the statistical power of survival analysis, an evaluation of the basic assumptions and the interaction between variables and time is important. In doing so, survival analysis can provide reliable scientific results with a high level of confidence.

Do Various Respirator Models Fit the Workers in the Norwegian Smelting Industry?

BACKGROUND: Respirator fit testing is a method to assess if the respirator provides an adequate face seal for the worker. METHODS: Workers from four Norwegian smelters were invited to participate in the study, and 701 respirator fit tests were performed on 127 workers. Fourteen respirator models were included: one FFABE1P3 and 11 FFP3 respirator models produced in one size and two silicone half masks with P3 filters available in three sizes. The workers performed a quantitative fit test according to Health and Safety Executive 282/28 with 5–6 different respirator models, and they rated the respirators based on comfort. Predictors of overall fit factors were explored. RESULTS: The pass rate for all fit tests was 62%, 56% for women, and 63% for men. The silicone respirators had the highest percentage of passed tests (92–100%). The pass rate for the FFP3 models varied from 19–89%, whereas the FFABE1P3 respirator had a pass rate of 36%. Five workers did not pass with any respirators, and 14 passed with all the respirators tested. Only 63% passed the test with the respirator they normally used. The mean comfort score on the scale from 1 to 5 was 3.2. The respirator model was the strongest predictor of the overall fit factor. The other predictors (age, sex, and comfort score) did not improve the fit of the model. CONCLUSION: There were large differences in how well the different respirator models fitted the Norwegian smelter workers. The results can be useful when choosing which respirators to include in respirator fit testing programs in similar populations.

Factors affecting the fit of respirators in the biosafety level 3 laboratory / 中华实验和临床病毒学杂志

Objective@#To test the performance of two kinds of protective respirators (3M9332, 3M1860) used in Biosafety Level 3 Laboratory (BSL-3) to ensure whether it can fit well in different populations in order to reduce the risk of infection in the process of operating high-risk pathogenic microorganisms.@*Methods@#Using a 8038PortaCount®Pro+ respirator fit tester to examine the fitness of personnel wear 3M 1860 N95 and 9332 N99 respirators. The influence factors such as gender, age, shape of respirator were evaluated. Statistical analysis was performed by the fit factor(FF) of assigned actions.@*Results@#A total of 62 people conducted the respirator fit test, of which 45 people passed the test of 3M9332 respirators, the pass rate was 72.58%; only 6 people passed the test of 3M1860 respirators, the pass rate was 9.67%. The pass rate of two different types of respirators was analyzed statistically, P=0.000. The P value of assigned actions in deep breathing, head side to side, head up and down, talking, bending over were respectively 0.094, 0.076, 0.542, 0.000, 0.000.@*Conclusions@#The experimental results showed that the type of respirator had a significant effect on respirator fit in this study, but gender and age had no significant effect on factors. As to reduce the risk of leakage of the respirator, redundant actions should try to be avoided, especially loud talking and bending in the course of the experiment.

Qualitative Fit Testing of High-Efficiency Particulate Respirators for Healthcare Personnel / 병원감염관리

BACKGROUND: This study purposed to survey the fit rate of respirators by person and by product through conducting a qualitative fit test of high-efficiency respirators; moreover, this study also tests for differences in the fit rates determined by the qualitative fit tests with an increase in the number of the types of respirators tested. METHODS: The subjects of this study were 30 healthcare personnel who had passed a sensitivity test. The fit test of high-efficiency respirators was conducted using FT10 (3M Co., USA), an experimental tool used for performing the qualitative fit test of high-efficiency respirators, and three types of high-efficiency respirators - 1860, PFR95, and N7000 - were tested. RESULTS: The qualitative fit test was performed for the three types of high-efficiency respirators and the fit rate of the respirators that the subjects had been using previously was 43.3%; however, the probability that one or more of the three types of high-efficiency respirators would fit the subjects increased to 83.3%, and this increase was statistically significant (P<0.05). The difference in the fit rates of the three types of high-efficiency respirator types was not statistically significant; however, the differences in the satisfaction of and preference for the different respirator products were all statistically significant (P<0.05). CONCLUSION: Healthcare personnel are using ill-fitting respirators and a qualitative fit test should be performed to improve the fit of their respirator. In the qualitative fit test performed for the high-efficiency respirators, the fit rate increased with the increase in the variety of respirator types. Thus, a large variety of respirators should be made available to increase the fit rate of high-efficiency respirators for healthcare personnel.

Correlation of Fit Factors for Respirators and Anthropometric Dimension / 예방의학회지

In many developed countries, for example, USA, respirator fit testing is required before entering specific work environment to ensure that the respirator worn satisfies a minimum of fit and that the user knows when the respirator fits properly. Unfortunately because we have not fit test regulation in Korea, a lot of workers wearing respirators may be potentially exposed to hazards. This study was conducted to evaluate the fitting performance for respirators and correlation fit factors with facial dimensions of wearers. 110 subjects (70 males, 40 females) were fit tested for three quarter masks, i.e., two domestic-made Mask Z, and Y and one foreign-made Mask T using PortaCount 8020. A facial dimension survey of the same subjects was conducted to develop a facial dimension grids for correlation fit factors with facial dimension parameters. A facial dimension grid was developed on the basis of face length and lip length for quarter masks. The results obtained were as follows: 1. Fit factors of Mask T were much higher than those of Masks Z, and Y. 2. Males were fitted more properly than females. 3. Male in box "f" of grid would be adequately fitted Mask Y and male in box "b", "e", "f", "h" of grid would be sufficiently fitted Mask T. Female in box "h" of grid may have a good fitting performance for both Mask Y, and T. But subjects in all boxes of grid would be inadequately fitted Mask Z.