Objective:To investigate the fit of dust-exposed workers wearing KN95 masks in a city of Guangdong Province, and to discuss the intervention effect of nose pads and elastic adjustment clasps on the fit of KN95 masks.Methods:In January 2024, 145 dust-exposed workers from a stone processing enterprise in a city of Guangdong Province were selected as study subjects by convenience sampling, and 4 types of KN95 masks commonly used by dust-exposed workers were selected as test masks. The head and face dimensions of the study subjects were measured using a right-angle gauge and a curved-angle gauge, and the fit factor (FF) of the KN95 masks was tested using the quantitative fit test for respiratory protective equipment, and the intervention of adding nose pads or elastic adjustment clasps was given to those who failed the first fit test. The paired t-test was used to compare the changes of workers' FF before and after the intervention. Results:The coverage rate of the study population in the facial subsection of the Chinese Han population was 71.0% (103/145). Before intervention, the overall passing rate of the fit test of 4 types of KN95 masks was 16.6% (24/145), and the passing rate of 4 types of masks had statistical significance ( χ2=19.73, P<0.001). After intervention, the overall passing rate of the fit test of masks was 33.9% (41/121), and the geometric mean of the total FF after intervention increased from 15.9 to 62.7 ( t=-13.53, P<0.001), among which 88.4% (107/121) workers' FF improved after intervention, and 11.6% (14/121) of workers had reduced FF. Conclusion:Dust-exposed workers in a city of Guangdong Province have a low coverage rate of facial subsection among Chinese Han population, and the passing rate of KN95 mask fit test is low. Interventions using additional nose pads or elastic adjustment clasps can partially improve the fit of the mask, and it is still necessary to continue to explore interventions to improve the fit of mask wearers.

Objective:To understand the current status of the actual protective effect of respiratory protective equipment (RPE) for workers exposed to trichloroethylene (TCE), and to explore the factors affecting the actual protective effect.Methods:From July to December 2023, a total of 75 workers occupationally exposed to TCE from 21 hardware and electronics manufacturing facilities in a province were selected as research objects by convenient sampling method. Workplace protection factor (WPF) was used as an index to evaluate the actual protective effect of workers' RPE. The concentration of TCE inside and outside the RPE was detected to calculate WPE, and the temperature, humidity and wind speed near the working place were measured, as well as the forced vital capacity, respiratory rate, heart rate and other indicators of the worker were measured. The log-transformed WPF value (lgWPF) followed a normal distribution. One-sample t-test was used to compare the difference between the mean lgWPF and the log value of the assigned protection factor (APF) of the half mask (lgAPF=1). Multiple linear regression model was used to investigate the influencing factors of lgWPF. Results:The lgWPF of 75 TCE-exposed workers ranged from 0.40 to 1.32 (0.84±0.22). The mean of lgWPF was lower than that of lgAPF, and the difference was statistically significant ( t=-6.37, P<0.001). After adjusting for confounding factors, the results of multiple linear regression showed that humidity, forced vital capacity and respiratory rate were negatively correlated with lgWPF ( β=-0.008, -0.079, -0.021, P<0.05) . Conclusion:The actual protective efficacy of RPE among workers exposed to TCE is suboptimal. High humidity, elevated forced vital capacity, and increased respiratory rate may be contributing factors to the diminished protective performance of RPE.

BACKGROUND:In most species,a bone defect that is longer than 1.5 or 2 times its diameter can be considered a critical bone defect,and when the bone defect volume reaches the critical value,it cannot heal on its own.Currently,there is no uniform standard for the size of critical-sized defects in the osteoporotic femoral condyle of rabbits.OBJECTIVE:To establish a rabbit model with different sizes of bone defects in the osteoporotic femoral condyle and to determine the critical-sized defects of osteoporotic femoral condyle in rabbits.METHODS:Thirty-six 3-month-old female New Zealand white rabbits were randomly divided into ovariectomy group(n=30)and sham operation group(n=6).Rabbits in the ovariectomy group underwent bilateral ovariectomy to establish an osteoporosis model,and then femoral condyle bone defect models of different diameters(diameters were 4,5,6,and 7 mm,and depths were 8 mm)were further established;rabbits in the sham operation group did not undergo ovariectomy.At 8 and 12 weeks after modeling,3 rats were randomly selected from each group for CT scanning and three-dimensional reconstruction to evaluate the healing of bone defects.Afterwards,samples were taken for gross observation and hematoxylin-eosin staining to observe the growth of new bone in the femoral condyle bone defect area.RESULTS AND CONCLUSION:(1)All rabbits survived and moved well after modeling of osteoporosis and femoral condyle bone defect.(2)At 12 weeks after osteoporosis modeling,dual-energy X-ray absorptiometry results showed that the bone mineral density of lumbar vertebrae in ovariectomy group was significantly lower than that in sham operation group(P＜0.05).Hematoxylin-eosin staining showed that the bone trabeculae in the ovariectomy group became thinner and sparse.The proportion of bone tissue area in the ovariectomy group was significantly lower than that in the sham operation group(P=0.00).Micro-CT results showed that the bone tissue parameters of the femoral condyle in the ovariectomy group were significantly different from those in the sham operation group(P＜0.05),and the ovariectomy group showed obvious characteristics of osteoporosis.(3)CT showed that the bone defect in the 4 mm and 5 mm diameter groups was basically completely repaired at 12 weeks after surgery.There was more new bone tissue in the 6 mm diameter group,but the central part of the bone defect was not completely repaired.A small amount of new bone tissue grew in the 7 mm diameter group,and the bone defect was obvious.(4)Gross observation at 12 weeks after surgery showed that the femoral condyle bone defect in the 4 mm and 5 mm diameter groups was completely repaired.Obvious depression was seen in the bone defect area of the 6 mm and 7 mm diameter groups,and the bone defect was not completely repaired.(5)Histological observation at 12 weeks after surgery showed that the bone defect area of the 4 mm and 5 mm diameter groups was completely filled with new bone,and the trabecular structure was irregular;while there were new trabeculae in the periphery of the 6 mm and 7 mm diameter groups,and the bone defect in the central area was still obvious.(6)The results showed that during the 12-week experimental observation period of osteoporotic femoral condyle defects in rabbits,under the condition of the same defect depth of 8 mm,femoral condyle defects with a diameter ≥ 6 mm could not heal on their own,while femoral condyle defects with a diameter＜6 mm were completely repaired.A diameter of 6 mm and a depth of 8 mm can be used as the critical bone defect value of osteoporotic femoral condyle in rabbits.

Objective:To evaluate the current situation of the protective effect of hearing protection device (HPD) worn by manufacturing workers and discuss their possible influencing factors.Methods:A total of 3634 noisy workers were surveyed and tested. The study conducted surveys of workers on the use of HPD. The 3M TM E-A-R Fit TM binaural verification system was used to measure the personal attenuation device (PAR) of workers wearing HPD. Results:The M ( Q1, Q3) of baseline PAR obtained by 3634 workers was 12 (2, 19) dB. There was a statistically significant difference in baseline PAR among the three types of HPDs ( H=336.39, P<0.01) . After pairwise comparison, it was found that the baseline PAR of workers wearing foam earplugs and earmuffs was higher than that of pre-molded earplugs ( P<0.01) . There were differences in baseline PAR among workers in different industries ( Z=359.73, P<0.01) . Education level, age of using HPD, types of HPDs, noise exposure intensity, with or without knowledge of correct methods, and comfort evaluation were the main factors affecting baseline PAR ( P<0.05) . There were 1536 workers (43.4%) failed the baseline PAR test. After the intervention, the median PAR increased significantly from 1 (0, 6) dB (baseline) to 18 (14, 22) dB (after the intervention) ( P<0.01) . The follow-up test found that the follow-up PAR of 328 workers was higher than the baseline PAR of the initial test, and the follow-up PAR was higher than the post-intervention PAR of the initial test ( P<0.01) . Conclusion:Under the conditions of this study, the protective effect of HPD was affected by factors such as incorrect understanding of wearing methods, exposure to high-intensity noise, low education level, a short period of time of HPD use and low comfort of hearing protectors. The protective effect could be improved through training, optimizing the wearing of hearing protector models, and follow-up interventions. Enterprises should use suitability verification to ensure the correct selection and wearing of noisy workers.

Objective:To Exploring the protective effect of hearing protectors worn by noise workers in the petrochemical industry and the factors affecting the protective effect of hearing protectors.Methods:From June 2021 to July 2023, 929 petrochemical workers were selected as the research subjects through cluster sampling. The noise exposure of workers and the usage of two types of hearing protectors were surveyed through questionnaire surveys and on-site occupational hygiene surveys. The protective effect of hearing protectors were evaluated by testing the PAR of workers. If the noise exposure value of workers minus the PAR value was less than 85 dB (A) , it was considered passed. Otherwise, it was considered not passed. The passing rate of the protective effect test of hearing protectors was analyzed through chi square test and the influencing factors for the effectiveness of workers hearing protectors in test were explored through single factor analysis and logistic regression models.Results:Among the research subjects, 80.5% of workers (748/929) had noise exposure levels greater than 85 dB (A) . The passing rate (80.9%) of the earmuff is greater than that of the earplug (52.6%) , and the median of PAR of the earmuff is 22 (16, 25) , which is greater than that of the earplug 15 (3, 22) dB dB, with a statistically significant difference ( P<0.001) . Univariate analysis and logistic regression models showed that length of service, exposure level to noise, and wearing comfort were the influencing factors of earplug protection effect ( P<0.05) , while wearing comfort was the influencing factor of earmuff protection effect ( P<0.05) . Conclusion:This study indicates that the protective effect of hearing protectors on workers in the petrochemical enterprise is poor, and the protective effect of earmuffs is greater than that of earplugs. Working experience, noise exposure level, and wearing comfort are the influencing factors of earplug protection effect, while wearing comfort is the influencing factor of earplug protection effect.

Objective:To evaluate the current situation of the protective effect of hearing protection device (HPD) worn by manufacturing workers and discuss their possible influencing factors.Methods:A total of 3634 noisy workers were surveyed and tested. The study conducted surveys of workers on the use of HPD. The 3M TM E-A-R Fit TM binaural verification system was used to measure the personal attenuation device (PAR) of workers wearing HPD. Results:The M ( Q1, Q3) of baseline PAR obtained by 3634 workers was 12 (2, 19) dB. There was a statistically significant difference in baseline PAR among the three types of HPDs ( H=336.39, P<0.01) . After pairwise comparison, it was found that the baseline PAR of workers wearing foam earplugs and earmuffs was higher than that of pre-molded earplugs ( P<0.01) . There were differences in baseline PAR among workers in different industries ( Z=359.73, P<0.01) . Education level, age of using HPD, types of HPDs, noise exposure intensity, with or without knowledge of correct methods, and comfort evaluation were the main factors affecting baseline PAR ( P<0.05) . There were 1536 workers (43.4%) failed the baseline PAR test. After the intervention, the median PAR increased significantly from 1 (0, 6) dB (baseline) to 18 (14, 22) dB (after the intervention) ( P<0.01) . The follow-up test found that the follow-up PAR of 328 workers was higher than the baseline PAR of the initial test, and the follow-up PAR was higher than the post-intervention PAR of the initial test ( P<0.01) . Conclusion:Under the conditions of this study, the protective effect of HPD was affected by factors such as incorrect understanding of wearing methods, exposure to high-intensity noise, low education level, a short period of time of HPD use and low comfort of hearing protectors. The protective effect could be improved through training, optimizing the wearing of hearing protector models, and follow-up interventions. Enterprises should use suitability verification to ensure the correct selection and wearing of noisy workers.

Objective:To Exploring the protective effect of hearing protectors worn by noise workers in the petrochemical industry and the factors affecting the protective effect of hearing protectors.Methods:From June 2021 to July 2023, 929 petrochemical workers were selected as the research subjects through cluster sampling. The noise exposure of workers and the usage of two types of hearing protectors were surveyed through questionnaire surveys and on-site occupational hygiene surveys. The protective effect of hearing protectors were evaluated by testing the PAR of workers. If the noise exposure value of workers minus the PAR value was less than 85 dB (A) , it was considered passed. Otherwise, it was considered not passed. The passing rate of the protective effect test of hearing protectors was analyzed through chi square test and the influencing factors for the effectiveness of workers hearing protectors in test were explored through single factor analysis and logistic regression models.Results:Among the research subjects, 80.5% of workers (748/929) had noise exposure levels greater than 85 dB (A) . The passing rate (80.9%) of the earmuff is greater than that of the earplug (52.6%) , and the median of PAR of the earmuff is 22 (16, 25) , which is greater than that of the earplug 15 (3, 22) dB dB, with a statistically significant difference ( P<0.001) . Univariate analysis and logistic regression models showed that length of service, exposure level to noise, and wearing comfort were the influencing factors of earplug protection effect ( P<0.05) , while wearing comfort was the influencing factor of earmuff protection effect ( P<0.05) . Conclusion:This study indicates that the protective effect of hearing protectors on workers in the petrochemical enterprise is poor, and the protective effect of earmuffs is greater than that of earplugs. Working experience, noise exposure level, and wearing comfort are the influencing factors of earplug protection effect, while wearing comfort is the influencing factor of earplug protection effect.

BACKGROUND:In most species,a bone defect that is longer than 1.5 or 2 times its diameter can be considered a critical bone defect,and when the bone defect volume reaches the critical value,it cannot heal on its own.Currently,there is no uniform standard for the size of critical-sized defects in the osteoporotic femoral condyle of rabbits.OBJECTIVE:To establish a rabbit model with different sizes of bone defects in the osteoporotic femoral condyle and to determine the critical-sized defects of osteoporotic femoral condyle in rabbits.METHODS:Thirty-six 3-month-old female New Zealand white rabbits were randomly divided into ovariectomy group(n=30)and sham operation group(n=6).Rabbits in the ovariectomy group underwent bilateral ovariectomy to establish an osteoporosis model,and then femoral condyle bone defect models of different diameters(diameters were 4,5,6,and 7 mm,and depths were 8 mm)were further established;rabbits in the sham operation group did not undergo ovariectomy.At 8 and 12 weeks after modeling,3 rats were randomly selected from each group for CT scanning and three-dimensional reconstruction to evaluate the healing of bone defects.Afterwards,samples were taken for gross observation and hematoxylin-eosin staining to observe the growth of new bone in the femoral condyle bone defect area.RESULTS AND CONCLUSION:(1)All rabbits survived and moved well after modeling of osteoporosis and femoral condyle bone defect.(2)At 12 weeks after osteoporosis modeling,dual-energy X-ray absorptiometry results showed that the bone mineral density of lumbar vertebrae in ovariectomy group was significantly lower than that in sham operation group(P＜0.05).Hematoxylin-eosin staining showed that the bone trabeculae in the ovariectomy group became thinner and sparse.The proportion of bone tissue area in the ovariectomy group was significantly lower than that in the sham operation group(P=0.00).Micro-CT results showed that the bone tissue parameters of the femoral condyle in the ovariectomy group were significantly different from those in the sham operation group(P＜0.05),and the ovariectomy group showed obvious characteristics of osteoporosis.(3)CT showed that the bone defect in the 4 mm and 5 mm diameter groups was basically completely repaired at 12 weeks after surgery.There was more new bone tissue in the 6 mm diameter group,but the central part of the bone defect was not completely repaired.A small amount of new bone tissue grew in the 7 mm diameter group,and the bone defect was obvious.(4)Gross observation at 12 weeks after surgery showed that the femoral condyle bone defect in the 4 mm and 5 mm diameter groups was completely repaired.Obvious depression was seen in the bone defect area of the 6 mm and 7 mm diameter groups,and the bone defect was not completely repaired.(5)Histological observation at 12 weeks after surgery showed that the bone defect area of the 4 mm and 5 mm diameter groups was completely filled with new bone,and the trabecular structure was irregular;while there were new trabeculae in the periphery of the 6 mm and 7 mm diameter groups,and the bone defect in the central area was still obvious.(6)The results showed that during the 12-week experimental observation period of osteoporotic femoral condyle defects in rabbits,under the condition of the same defect depth of 8 mm,femoral condyle defects with a diameter ≥ 6 mm could not heal on their own,while femoral condyle defects with a diameter＜6 mm were completely repaired.A diameter of 6 mm and a depth of 8 mm can be used as the critical bone defect value of osteoporotic femoral condyle in rabbits.

Objective:To investigate the fit of dust-exposed workers wearing KN95 masks in a city of Guangdong Province, and to discuss the intervention effect of nose pads and elastic adjustment clasps on the fit of KN95 masks.Methods:In January 2024, 145 dust-exposed workers from a stone processing enterprise in a city of Guangdong Province were selected as study subjects by convenience sampling, and 4 types of KN95 masks commonly used by dust-exposed workers were selected as test masks. The head and face dimensions of the study subjects were measured using a right-angle gauge and a curved-angle gauge, and the fit factor (FF) of the KN95 masks was tested using the quantitative fit test for respiratory protective equipment, and the intervention of adding nose pads or elastic adjustment clasps was given to those who failed the first fit test. The paired t-test was used to compare the changes of workers' FF before and after the intervention. Results:The coverage rate of the study population in the facial subsection of the Chinese Han population was 71.0% (103/145). Before intervention, the overall passing rate of the fit test of 4 types of KN95 masks was 16.6% (24/145), and the passing rate of 4 types of masks had statistical significance ( χ2=19.73, P<0.001). After intervention, the overall passing rate of the fit test of masks was 33.9% (41/121), and the geometric mean of the total FF after intervention increased from 15.9 to 62.7 ( t=-13.53, P<0.001), among which 88.4% (107/121) workers' FF improved after intervention, and 11.6% (14/121) of workers had reduced FF. Conclusion:Dust-exposed workers in a city of Guangdong Province have a low coverage rate of facial subsection among Chinese Han population, and the passing rate of KN95 mask fit test is low. Interventions using additional nose pads or elastic adjustment clasps can partially improve the fit of the mask, and it is still necessary to continue to explore interventions to improve the fit of mask wearers.

Objective:To understand the current status of the actual protective effect of respiratory protective equipment (RPE) for workers exposed to trichloroethylene (TCE), and to explore the factors affecting the actual protective effect.Methods:From July to December 2023, a total of 75 workers occupationally exposed to TCE from 21 hardware and electronics manufacturing facilities in a province were selected as research objects by convenient sampling method. Workplace protection factor (WPF) was used as an index to evaluate the actual protective effect of workers' RPE. The concentration of TCE inside and outside the RPE was detected to calculate WPE, and the temperature, humidity and wind speed near the working place were measured, as well as the forced vital capacity, respiratory rate, heart rate and other indicators of the worker were measured. The log-transformed WPF value (lgWPF) followed a normal distribution. One-sample t-test was used to compare the difference between the mean lgWPF and the log value of the assigned protection factor (APF) of the half mask (lgAPF=1). Multiple linear regression model was used to investigate the influencing factors of lgWPF. Results:The lgWPF of 75 TCE-exposed workers ranged from 0.40 to 1.32 (0.84±0.22). The mean of lgWPF was lower than that of lgAPF, and the difference was statistically significant ( t=-6.37, P<0.001). After adjusting for confounding factors, the results of multiple linear regression showed that humidity, forced vital capacity and respiratory rate were negatively correlated with lgWPF ( β=-0.008, -0.079, -0.021, P<0.05) . Conclusion:The actual protective efficacy of RPE among workers exposed to TCE is suboptimal. High humidity, elevated forced vital capacity, and increased respiratory rate may be contributing factors to the diminished protective performance of RPE.