Development of a device to reduce the risk of injury in handling unstable loads.

BACKGROUND: Manual material handling (MMH) task is the most common cause of work-related musculoskeletal disorders (MSDs). Operators carrying unstable loads were recently shown to be at greater risk of back injury compared to workers carrying stable loads. OBJECTIVE: This study focused on developing a device to minimize trunk muscle activity and cardiovascular demand while handling a 19-liter bottle. METHOD: After evaluating several designs, one was selected to be developed, manufactured and tested through an experimental study. Healthy participants (n = 42) manually carried a 19-liter bottle. The carrying technique (i.e., carrying a lateral load while holding the load using the dominant hand, pulling the load using the developed device, carrying the load on the back using the developing device) was the independent variable. The muscular activities (e.g., neck extensor, upper trapezius, pectoralis major, deltoid medial, rectus abdominis, and erector spinae muscles of the dominant side), cardiac costs, plantar pressures, walking speeds, and subjective measures were the dependent variables. RESULTS: Results show that carrying the developed device like a backpack significantly reduced trunk muscle activity, cardiovascular demand, and plantar pressure compared to the usual practice. The present results suggest that carrying a 19-liter water bottle using the developed device is likely to contribute to lower MSDs. CONCLUSION: Implementation of the develop device recommended to lessen the risk of injury when handling unstable loads such as liquids.

How many days are required for workers to acclimatize to heat?

BACKGROUND: Many research studies require recruiting heat-acclimatized workers to participate in heat-stress experiments and application fields. A reliable heat acclimatization program for workers in countries with hot environments has not been reported yet. OBJECTIVE: The objective of this study was to estimate the effects of heat stress and the amount of acclimatization required in hot-climate countries. METHODS: Eighteen male workers from an industrial population participated in this experiment. Nine days of exposure to a hot environment (wet-bulb globe temperature, 30°C) was the independent variable. The participants' cardiac costs and increment aural-canal temperatures were the dependent variables. RESULTS: The study results revealed that 5 days of exposure to heat sessions were sufficient to heat acclimatize the workers based on their physiological responses (i.e., heart rate and aural-canal temperature). CONCLUSIONS: According to the available literature, workers in hot climate countries, similar to the study cohort, can heat acclimatize faster than those in other Western countries.

The association of sleep deprivation on the occurrence of errors by nurses who work the night shift.

PURPOSE: To determine the influence of sleep deprivation on the occurrence of errors by registered nurses working in night shift in intensive care departments. METHODS: The study utilized a multi-part questionnaire which included items about demographic characteristics, reported medical errors, and Pittsburgh Sleep Quality Index (PSQI) 300 questionnaires were distributed to registered nurses working in intensive care departments. 138 of the 153 (51% response rate) collected questionnaires were analyzed using correlation and stepwise logistic multiple regression. RESULTS: Registered nurses who were sleep deprived had worse sleep quality in terms of high PSQI than those who were not. None of the demographic variables was statistically significant, not providing evidence that these variables may explain odds for being sleep deprived in the population. CONCLUSIONS: Work schedule changes, offering shorter periods of time on night shift and less working hours in the week may lead to better sleep quality and less sleep deprivation.

Effects of protective respiratory devices and physical workloads in harsh weather conditions on individuals' physiological measures and exertion ratings.

OBJECTIVE: Although respiratory device is an essential item to protect the wearer from hazardous gases and dust, it tends to increase heat load on the workers. The goal of this paper was to select the appropriate respiratory devices that can be used in a harsh weather under different work-loads. METHODS: Sixteen young male participants participated in this study. Participants exercised on an ergometer bike in a laboratory at 30% and 50% of their physical workloads, in temperature and humidity controlled environments (30°C and 40°C dry bulb temperatures with 50% and 90% Relative Humidity), while wearing six different respiratory devices. The effects on the participant's body functions (e.g., heart rate, aural canal temperature and blood pressure), and their subjective exertion ratings were measured. RESULTS: Results proved that when wearing protective devices in hot environments, all physiological measures as well as exertion ratings were significantly increased. However, wearing half-face masks with two inlets exerted less stresses on the worker's physiological measures and subjective rating. CONCLUSIONS: This study recommended wearing half-face masks with two inlets to be used when performing tasks at hot environmental conditions.

Does Saudi school furniture meet ergonomics requirements?

OBJECTIVE: The goal of this research was to study the effect of adjustable imported desk and chair combinations available in the market on student performance. METHODS: Six sets of chairs and tables within three different activities (reading, writing, and looking to the blackboard) were the independent variables. Evaluation of back force at 5th lumbar vertebrae and the 1st sacrum (L5/S1), subjective measures of discomfort, and the mismatch between student body dimension and classroom furniture analysis were measured. PARTICIPANTS: A total of 124 young male students (first through sixth-grade) participated in this experiment. RESULTS: The results revealed too low or too high chair and table heights relative to the students' body dimensions increased the stresses acting at L5/S1 as well as discomfort ratings. CONCLUSIONS: This study indicated there was a high level of body mismatch in desk-chair combinations even with the adjustable imported furniture available in the local market. Anthropometric data of Saudi students should be collected from different regions in the Kingdom and then design and development of desk-chair combinations could follow the development of a standard procedure to adapt to the needs of Saudi school children.