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Upper limb work related musculoskeletal disorders (ULWMSDs) are one of the leading causes of occupational injuries and disabilities in industrialized and developing countries (1-3). If work is carrying out repeatedly, in the non-ergonomic workstations and with awkward body positions (postures) in long-term, risk of musculoskeletal disorders in users will increase significantly.
In the United States of America, lack of attention to ergonomic principles and factors that cause musculoskeletal disorders led to $ 15-20 billion cost per year and had a 34% working days lost, also, the average time to return to work after the hospitalization and treatment of these disorders was 28 days (4). According to Health and Safety Executive (HSE) in a one-year period between 2004 and 2005, it was estimated that 28.4 million working days were lost due to neck, shoulder and back occupational disorders. Each worker was away from work for an average of 23 days and 7.5 billion pounds has been spent for damages (5). In addition, it was the most common cause of employee absenteeism (6). The researchers (7) stated that the cost of musculoskeletal disorders in Iran was 7.6% of the country's budget in 2000. It should not be forgotten that the indirect costs of accidents, such as loss of productivity and loss of customer satisfaction, is four times more than the direct costs (8). Due to the effects of fatigue, burnout and early analysis and more economically, the loss of time and increase in normal production costs, optimization of the interaction and balance between employee and workplace is one of the concerns of experts. Economic losses resulting from this disease impacts not only on individuals, but also organizations and society and reduces the productivity of employees (9,2).
musculoskeletal disorders Risk factors, including occupational activity like manual handling heavy loads, repetitive motions, poor work posture (10-12) and also psychological, organizational and individual (12). In general, ergonomic risk factor in the workplace which employees faced with such as force exertion, repetitive work, and contact stress. Exposure with these types of risk factors in the workplace leads to a series of disorders such as elongation and tear muscle, strain or tendonitis and joint pain, back pain, herniated disc, spinal cord injury and other musculoskeletal problems. These conditions may gradually or suddenly created by activities such as lifting a heavy load, leading to pain, disability or loss of jobs. Studies have shown that the best way to prevent WMSDs, intervention to reduce exposure to risk factors such as repetitive motion, excessive force, awkward postures, vibration exposure and static activities. On this basis, risk factors for WMSDs should be considered and evaluated at the workstations (13).
Therefore, a method that is able to pay attention to series of risk factors (physical, mechanical, organizational, psychological and social, individual and personal) (14) and provide the level of risk, can improve decision-making and is very effective. Sometimes easier assessment methods are more efficient than complex ones. In the scientific literature, direct measurement of musculoskeletal damages (with methods such as EMG) (15) as well as methods based on biomarkers of musculoskeletal disorders (16) or internal load evaluation methods such as body temperature, heart rate and blood pressure (14), besides observational methods (external evaluation) (17), are methods to evaluate ergonomic risk factors and musculoskeletal injuries.
Although some researchers have criticized the widespread use observational tools but used many epidemiological risk factors with high stability by these methods and using self-report and observational or pen -paper methods have been evaluated sufficient for epidemiological purposes (18). In addition, cost of these methods is estimated as one-tenth of direct methods and it is possible to choose more samples with a similar budget (15).
Upper limb disorders are very common, and 20-30 percent of working population has experienced it [18]. ULWMSDs are observed in occupations with high amount of manual tasks (18). ART method as an indicator for measuring the external load on upper limbs is one of the new tools that as well as Stress Index (SI) (19), Upper Limb Risk Assessment (ULRA) (20), Occupational Repetitive Action Index (OCRA) (21), can be used to assess load on upper limbs with parameters of posture, force and time sequence (14,22). Some studies (23) demonstrated application of ART method practically and proposed it as a usable, easy and convenient method for purposes of evaluation and ergonomic interventions in the repetitive work task. Karimi and colleagues also said that ART is a valid method to assess ergonomic risk factors in repetitive tasks and its results was confirmed by the results of the Nordic questionnaire (24).
Aims of the study:
This study aimed to evaluate tasks ergonomically and provide associated risk factors studied in an Arc Opal dishes manufacture company in Kashan using Assessment of Repetitive Tasks (ART) tool as a new method and was conducted in 2014-2015.
 

Materials & Methods

The study was cross-sectional and descriptive and analytical. A total of 240 personnel working in seven production halls, who had run a total of 13 types of tasks were studied by randomized sapling method.
It is noteworthy that tasks were identified through the documentation in the process department of the company and statuses of tasks in different halls were analyzed. Exclusion criteria including joint problems such as arthritis, herniated disc, disc infection, fracture in spine, other musculoskeletal problems and pain in different parts the body and were identified through interviews and self-report. To gather data on demographics, researchers-developed questionnaire including age, gender, work experience and training courses related to ergonomics and work was applied. Body map questionnaire was used to study musculoskeletal disorders (25). This questionnaire seeks the issue that musculoskeletal disorders have focused on which parts of the body. Furthermore, ergonomics risk factors have been assessed by ART method. T test, chi-square test and analysis of variance were utilized for statistical analysis of obtained data through SPSS V.20.
ART tool was introduced by Health and Safety Laboratory (HSL) in collaboration with Health and Safety Executive (HSE) in 2007. This tool is a appropriate method to study the upper limbs in repetitive tasks (26). The applicability of this tool has been approved by users and experts (26). Assessment through this method consists of four parts (27).
Frequency and repetition, force, awkward postures and additional factors and qualitative and quantitative assessment is carried out for each step. Any privilege mode takes specific score in quantitative evaluation and three levels of low, medium, and high risk would be defined in qualitative evaluation (27). Its final score (0-72) form t three levels: 0-11: low, 12-21: moderate and more than 22 are high risk level (27).
 

Results

The conducted analysis revealed that 124 (51.67%) of participants (240) was female and the rest are men. The mean age was 28.02±5.53 and in the range of 57-18 years.
Work experience of employees was 4.54 years on average with a standard deviation of 3.72 years. In addition, participants had tool part on average 0.64 (±0.71) on ergonomics or work training. 225 participated employees (93.8%) were right hand and others were left hand. Information on studied halls and conditions of responders in terms of education level is shown in table 1.

Variable		Frequency	%
Hall	Pars pack	47	19.6
	Pars Naghsh	26	10.8
	Packaging	3	1.2
	Leher	28	11.7
	Tempering	19	7.9
	Gradation	33	13.8
	Decoration	84	35
Education level	Up to diploma	58	24.2
	Diploma	137	57.1
	Associate's degree	21	8.7
	Bachelor and higher	24	10

 
 
 206 (85.8%) workers have experienced of work-related musculoskeletal pain at least in one part of the body during the past year. Among the different body parts that were examined in this study, lower back with 126 (52.5%), neck (35 percent) and right hand shoulder with about 33% were the most common problems in the musculoskeletal system. On the opposite side, right and left hips respectively with 3.6 and 1.7 percent had the least problems. Table 2 provides the complete information in this regard. Significant differences in musculoskeletal disorders among different groups regard to demographic variables were not demonstrated (p>0.05). Except for gender groups, the difference was statistically significant (p<0.05) in the sense that the number of parts with pain in females were more than in males (0.98 against 0.72, on average).
In addition, differences between musculoskeletal problems in different areas of the body between men and women were tested with chi-square and analysis results are depicted in table 3.
Average of final score of ART method on all samples was 30.07 (±43.12) (in the range of 39-6). Among the 240 examined cases, 179 ones (6.74%) were in the high risk area, 33 (8.13%) at moderate risk, and 11.7 percent (28 cases) have located at low levels of risk.
Among the studied manufacturing facilities, in degradation hall risk level as medium and Pars Naghsh was low; other sectors have been achieved high risk level. Table 4 shows the descriptive information of various factors and total score of ART in different salons and total assessed employees.
Arm movements and repetition factors had undesirable conditions in various halls in term of the large numbers of maximum score (ie, 6). Detailed assessment results of factors involved in ART method can be seen in table 4. The differences in the ART’s score, using t-test, it was found that the differences between men and women is significant (p<0.05) it means women had higher scores (36.43 against 23.25 on average). The final score of the seven studied sectors in terms of ART score are significantly different (p<0.05). However, final score difference analysis between workers with musculoskeletal disorders and without it using t-test, indicated it was not significant (p>0.05). On further investigation it was determined that final score of ART differences between people with problems and pain in neck, lower back, hands, shoulder and forearm and it is statistically significant (p<0.05) (table 2) and responders who have problems in these areas had higher ART’s final score.
 

Table 2( Musculoskeletal disorders description and P-values of ART's scores differences (n=240)

Body part		Frequency	%	P-value		Body part		Frequency	%	P-value
Back	Upper	32	13.3	0.651		Hand	R.	39	16.2	0.004
	Lower	126	52.5	0.009			L.	34	14.2	0.019
Shoulder	R.*	79	32.9	0.010		Tight	R.	42	17.5	0.406
	L.*	66	27.5	0.139			L.	41	17.1	0.104
Arm	R.	32	13.3	0.640		Knee	R.	68	28.3	0.135
	L.	23	9.6	0.280			L.	65	27.1	0.033
Elbow	R.	54	22.5	0.009		Bottom	R.	17	7.1	0.164
	L.	38	15.8	0.058			L.	15	6.3	0.239
Neck		84	35	0.001

*Note: R: Right, L: Left
 
 
 
Table 3) Musculoskeletal disorders differences between males and females using Chi-squared test

Body part		P-value		Body part		P-value
Back	Upper	0.561		Hand	R.	0.000
	Lower	0.025			L.	0.001
Shoulder	R.*	0.000		Tight	R.	0.417
	L.*	0.001			L.	0.757
Arm	R.	0.013		Knee	R.	0.010
	L.	0.068			L.	0.002
Elbow	R.	0.000		Bottom	R.	0.257
	L.	0.000			L.	0.224
Neck		0.000

 
 
 
 
 
 
 
 
 
 
 
 
*Note: R: Right, L: Left
 
Table 4) ART's score in terms of its criteria and in studied halls (n=240)

Total	duration	other factors such as vibration	work pace	breaks	hand/finger grip	Wrist posture	Arm posture	back posture	neck/head posture	force	repetition	arm movements	Criteria   Halls (n)
3	1	2	2	8	0	2	0	2	2	5	6	6	Pars pack (19)
6	0.5	1	1	4	0	1	0	1	1	0	3	0	Pars Naghsh (28)
39	1	1	2	8	1	2	2	1	2	8	6	6	Packaging (47)
22	1	0	1	0	2	2	4	2	2	0	6	3	Leher (3)
30	1	2	1	0	0	2	4	2	2	5	6	6	Tempering (26)
13	1	2	1	0	0	2	0	0	2	0	3	3	Gradation (33)
39	1	2	2	8	1	2	2	0	2	8	6	6	Decoration (84)
30.07	0.94	1.66	1.62	5.47	0.57	1.88	1.58	0.71	1.88	5.3	5.24	4.85	Mean	Total
12.43	0.16	0.5	0.48	3.47	0.52	0.32	1.28	0.78	0.32	3.4	1.31	2.06	SD
6	0.5	0	1	0	0	1	0	0	1	0	3	0	Min
39	1	2	2	8	2	2	4	2	2	8	6	6	Max