نجف نوریزاده

Firefighting is one of the occupations that require high physical and aerobic power due to the nature of the job and the physical demands of this profession. Therefore, the present study aimed to investigate the relationship among Work ability index (WAI), mental workload, musculoskeletal disorders (MSDs) and their effective factors in firefighters.

 This study was a cross-sectional study, which was carried out on 250 firefighters in Tehran. Data were collected using WAI, NASA-TLX and Body Discomfort Chart (BDC). Data analysis was carried out using descriptive statistics, linear regression, Pearson correlation and Spearman tests.

The mean and standard deviation of the total WAI score was 38.85±1.17. Also, the highest amount of mental workload was devoted to the physical load dimension (93.49±8.93). Meanwhile, the total mental load was also 70.07 ± 6.58. The results showed that the WAI is increased by 0.14 by augmentation of one unit at the academic level of firefighters (P = 0.03). The most common discomfort was reported in the lower (20%) and upper (16.8%) regions of the back. The total WAI relationship with total mental workload was positive and insignificant (P>0.05). There was a significant and reverse association between WAI and discomfort in wrist, leg and ankle.

Despite the low rate of MSDs, even mild symptoms of musculoskeletal pain should be considered. Given the high level of mental workload, improving physical, psychosocial and social working conditions is important in increasing the ability of employees and augmenting the ability of their occupational activity.

The application of computer codes and numerical modeling in studies and industry is growing. When using computer codes, the accuracy of these encodings and modelings are big questions. Comparing the results of the software with experimental results is the best method of evaluating these programs. The objective of this study was to experimentally validate a software program developed for local exhaust ventilation design.
In this experimental study, seven different local exhaust ventilation systems were designed and constructed. Velocity pressure, static pressure, total pressure and air velocity were measured at key points of each system. All measured values were compared with similar calculated values by computer software. One-sample T test and Bland Altman plot were used to compare the similar measured and computed parameters. SPSS version 19 was applied for statistical analysis.
The percentage difference of measured and calculated air velocities at all channels and hoods were ignorable with maximum amount of 0.5%. Difference between the measured and the calculated values of velocity pressure, static pressure and total pressure in the entire systems were less than 5 percent. Bland-Altman plot and one sample T test showed that the differences were in the range of 2SD and confirmed matching.
The results revealed that the air velocities measured with Pitot tube are much more accurate than those measured by thermal anemometer with maximum difference of 14.7%.
This study showed that the tested software has an acceptable accuracy with less than ± 5% of error. It also revealed that the application of Pitot tube is much more accurate that thermal anemometer.

work related musculoskeletal disorders are the most wide spread type of occupational diseases among workers. Awkward body postures during work and manual material handling are among the most important risk factors of musculoskeletal disorders in different jobs. Due to importance of recognizing these factors prevalence and risk factor of work related musculoskeletal disorders, this research was aimed to study the among employees of Kashan City’s Saipa automobile industry in 2011. This study is a descriptive-cross sectional study conducted among workers with manual material handling 37 activities and 84 work duties. To recognize musculoskeletal disorders, body map questionnaire was applied and occupational risk factors were evaluated using Key Index Method (KIM). Data was analyzed using SPSS and Excel software. Highest prevalence of musculoskeletal disorders was in low and upper back region (%92). Based on the results from KIM, workers in the installing the tire, shuttle-aided fitting of seat, and engine work station had higher risk level with the scores of 66, 52 and 52, respectively. Risk level among three individuals (%3.6) was at 1, 40 (%47.6) at 2, 38 (%45.2) risk level 3, and 3 (%3.6) at 4. Awkward body posture, improper twisting and flexion of low back were major risk factor among worker doing manual material handling tasks. Regarding the high prevalence of musculoskeletal disorders, appropriate ergonomic interventions such as engineering and organization interactions can reduce this risk factors (posture, heavy load, duration, workplace conditions) as much as the risk level reach to an acceptable level.