# Introduction onstruction industry is one of the more hazardous and risky occupations in terms of safety and health. Workers in the industry work under tough conditions to perform the desired task. The workers are frequently exposed to awkward work postures, physical demands and different types of diseases and accidents. They are more than twice as likely to be killed at work, than the average worker. Among the most common diseases is Work related Musculoskeletal Disorders (WMSDs) (Helen et al. 2008;Aman et al., 2011;David et al., 2010;BLES, 2010). The physical hazards always leading to increased risk of Musculoskeletal Disorders (MSDs) (NIOSH, 2011). Tasks that are either physically demanding or require repetitive lifting are at a high risk for accident-injuries. One situation that regularly cause worker to report back pains or to actually sustain injury is where an event that is not anticipated cause an injury while performing the task, example is the straining of back muscles by improper lifting (Articlesbase, 2011). Task may be considered hazardous if the imposed loads (forces) exceed the individual's strength and endurance/ tolerance (Chafin and Andersson, 1991). It was noted that the risk of injury is largely determined by the weight lifted (MHOR, 1992). Basra and Crawford (1995) observed variety of different handling techniques within the 131 employees in one brick manufacturing plant of which some of the techniques were considered potentially harmful. Construction Industry Advisory Committee (CONIAC, 1993) stated that there is a high risk of injury in the single-handed, and repetitive manual handling techniques of blocks heavier than 20 kilograms. As emphasized by Kerst (2003), effects of repetitive motions coupled with the performance of the same tasks are increased when awkward postures and forceful exertions are involved. It was however stated that ergonomics involvement tends to lower the physical demands of work tasks, thereby lowering the incidence and severity of injuries (Ajimotokan, 2008). Ergonomics must be targeted to each individual worker and the tasks that he or she performs. It is also important to take into account the physical abilities of each worker as well as their personal limitations (Articlesbase, 2011). One way to minimize risk to health or safety in construction work is by changing the way the work is done (WHSR, 2011). The Work Health and Safety (WHS) regulations place obligations on administrators carrying out of high risk construction work to ensure that a Safe Work Method Statement (SWMS) is prepared before the proposed work commences. The document should state among others the health and safety hazards and risks arising from the work to be carried out and describe how the risk control measures will be implemented, monitored and reviewed (CWCP, 2012). All employers are to devise safe working methods and communicate to all of the necessary workers on site and which have to be updated as the construction work progresses (TS, 2013). It is therefore the responsibility of site supervisor to supervise the safe work procedures and workers also are trained to follow such safe work techniques. There has been a number of research works after the limits established by International Labour Office (NIOSH,191). Load that nearly all healthy workers could perform in a specific set of task conditions over a substantial period of time without an increased risk of developing lifting-related low back pain was highlighted as Recommended Weight Limit (RWL) (Waters et al., 1993). This limit as described (Waters et al., 1994), proved useful for identifying certain lifting jobs that posed a risk to the musculoskeletal system for developing lifting related low back pain. Using NIOSH equation involves calculating Single task Recommended Weight Limit (STRWL) and Single-task Lifting Index (STLI) Waters et al., 1993) (APPENDIX A1) for the factors in the equation for a particular lifting and lowering task. If the magnitude of the lifting index (LI) increases, the level of the risk for the worker performing the job would be increased and a greater percentage of the workforce is likely to be at risk for developing lifting-related low back pain. The goal should be to design all lifting jobs to achieve a LI of 1.0 or less (Waters et al., 1994). # a) The aim and objectives of the study The aim of this study is to determine the level of inclusion of ergonomics in the work methods of some selected lifting related tasks in construction industry. The objectives of the study are too; 1. Determine the prevailing ergonomics risk factors contributing to lifting-related injuries among the group of tasks. 2. Determine the cause of prevalence of lifting related pains among the group of workers. II. # Material and Methods # a) Study Site and Task A worker participatory approach was used in this study. Two hundred and fifty male workers from ten construction sites in the Southwestern Nigeria volunteered to participate in the study. All participants were experienced workers in manual material lifting jobs and the tasks selected for the study were tasks performed regularly, for a long time without major changes and that conform to the application of the RWL. Thirty two lifting-related jobs which involved two-handed and none required of significant amount of non-lifting physical demands were included in the study. Some of the tasks included; brick setting, kern setting, lowering bricks from truck bed, loading wheelbarrow with bricks, Lifting head pans filled with mortars, lifting and fixing window blade, ceiling fan, fluorescent holders, setting perforated bricks, wall tilling, lifting and fixing wooden doors, Stacking concrete bricks, among others. Weight of materials lifted ranged from 2kg to 42kg. # b) Data Collection i. Demographic Information and Assessment of Work Outcomes A structured interview which followed a set of standardized questionnaires was conducted at the workers by trained personnel. Data collection was conducted at the construction sites during the working period and at a time agreed by the workers and the site managers. Data collection procedures consist of the assessment of demographic information of the workers, data related to level of ergonomics training received by the workers and the health outcome for workers who spent at least 2 years on the current lifting jobs. Workers were asked of their age and the number of years spent on the current job. Inclusion of ergonomics in the job methods was verified by the frequency of ergonomics related information/training made available to workers through their supervisors. Workers' responses to introduction of new methods of lifting were also examined. Nordic Musculoskeletal Symptom Survey (Kuorinka et al.,1987) was also used, inform of a questionnaire, taking into consideration the information concerning the subjective pain/discomfort so as to record the presence or absence of any lifting related pains in lower back, upper back, hips/upper legs, knees/lower legs, ankles/feet, neck, shoulders, elbows/forearms, wrists /hands, and fingers within the past 12 months. ii. Assessment of Lifting Task Parameters Reliable measurements are obtained if standardized measurement methods are used (Kuorinka et al., 1987). For reliability, personnel trained to make measurement in a standardized manner were involved in the measurement of variables of the selected tasks. In each of the selected job the following variables were recorded: weight of the lifted object (kg) using a weighing scale, frequency of the lift (lift/min) with the use of stop watch, task duration (hour) with wrist watch, vertical and horizontal distances (cm) both at the origin and destination of the lift with meter rule, coupling rating by observation, asymmetry angle (degree) both at the origin and destination of the lift with the use of goniometer. The frequency of lift was counted within the sample period of 15minutes. Data obtained from the workers were used for the calculations of STLI using the revised National Institute for Occupational Safety and Health (NIOSH) lifting equation. Horizontal Multiplier (HM), Vertical Multiplier (VM), Distance Multiplier (DM) and Asymmetric Multiplier (AM) were obtained with the use of equations as stated in APPENDIX A1 while Coupling Multiplier (CM) and Frequency Multiplier (FM) were derived using tables in APPENDIX A2 and A3 respectively. All the tasks were analyzed both at the origin of lift and at the destination. # Global Journal of Researches in Engineering XIII Issue v v III Version I Two hundred and thirty three (93.2%) of the two hundred and fifty (250) workers that participated in the study completed the questionnaire all of which have spent not less than 2 years on the current job. The demographics of the workers who participated in the studies are presented in Table 1. # Results It appears that the average STRWL values in the four categories of LI are similar in magnitude (6.86, 6.42, 7.83, and 6. 3). In the study 40 (63.5%) out of 63 workers that fall into category of 03 who complained of pain in the same body region. Category of 0
  • 3 where 50 (74.6%) out of 67 workers reported having lower back pain lasting more than one week in the past 12months. of the reported pain in body regions within the past 12 months Pains at the shoulder region of the body were reported by workers fixing window blade, ceiling fan and fluorescent holder with 54.5% of the workers in the category 03 were also reported suffering from shoulder pain as a result of the repetitive work. About twenty seven percent (27.3%) of workers in the category of 0
  • 3 and 20 (37.0%) of 54 workers are in the category of 2
  • 3. No worker in the categories of 03 category which were also the youngest among the group. Workers in the category of 03, the same group also suffered from shoulder pain because the nature of their jobs required having the load sustained at hands for some times at a height above the head. Mortar lifting, brick lifting, brick setting and fixing wooding doors tasks are mostly affected in this group. The high LBP complaints could be as a result of the magnitude of load lifted and low variable multiplies recorded among the category of workers. One of the important proposed applications of the lifting equation is as a tool for estimating the percentage of workers involving in lifting related jobs that is likely to be at risk for developing lifting-related low back pain (LBP). It has been raised that most of the working population should be able to perform jobs with LIs less than 1.0 without a significant risk of LBP and that the risk begins to increase as the LI exceeds 1.0. It is therefore necessary to consider possible ways of reducing the values of LI for all the jobs evaluated. A total redesign of workplace and job methods is very essential. Administrators in the industry need to incorporate ergonomics into the job methods most especially by intensifying efforts in training the workers on safe methods of manual material lifting among other safety trainings. All the multipliers must be given attention most importantly HM and FM in all categories to bring the values to 1.0 and less. The weight lifted by workers can be reduced by ensuring the containers are not fully loaded at the lifting point. Possibility of resizing the lifting containers can be conceived. Vertical multiplier can be increased by raising the origin of lift most especially while working above. This will increase the VM making it better than lifting from the lowest layer. Bringing the load as close as between the workers' leg could make a significant positive change. The angle of twist should be reduced to increase AM by moving the origin and destination closer together. The physiological demands can decrease by reducing the frequency rate of lift. Increasing number of mortar carriers, for instance, can be helpful in this measure so that demand on one worker will reduce. These corrections will decrease the values of LI below 1.0, reduce the risk of work related injuries and increase the quality of the task. V. # Conclusion Seventy-six percent (76%) of the lifting-related jobs studied had LI greater than 1.0 showing that the entire individual tasks in the groups have excessive physical stress that is connected with the jobs for nearly all healthy workers performing them and will result in physical fatigue. It is significant from this present study that most of the stress related complaints in construction works are engineered by poor work methods leading to high frequency of lift, lifting heavy loads at awkward postures among other factors. It can be concluded that manual handling in construction industries still have a significant level of higher physical stress associated with the jobs. There is a wide gaps in information related to the prevention of construction site injuries and illnesses among the workers. The tasks analysis results indicated that the involvement of ergonomics in studied construction sites is very low. Most workers performing the manual lifting job will be at an increased risk of a work-related injury. Among all the jobs analyzed, the highest LI values were recorded in mortar lifting tasks. ![1964) to reduce injuries, especially Low Back Pain (LBP) associated with manual load lifting. Work Practices Guide for Manual Lifting was published in 1981](image-2.png "") 1![Figure 1 : Description of the Response of workers to ergonomics related training Therefore through regular information/training, only thirty-one workers representing 13.3 percent of the total workers who participated in the study are probably exposed to ergonomics/ safe method of lifting. b) Work-related pain prevalence among the workers Regarding work-related pain prevalence among the workers, 170 workers (73%) out of 233 workers fall into categories of LI>1 (Table3). In the study 40 (63.5%)](image-3.png "Figure 1 :") 1 2Lifting Equation Values for Jobs with Workers on CurrentJob ? 2 year, by Lifting Index (LI) categoryLifting Index CategoryDemographic Variable03No. of Jobs9788Single TaskRecommended Weight Limit6.864(2.088) 6.42(2.24)7.83(3.41)6.23(2.34)(STRWL)Mean Lifting index0.52(0.27) 1.48(0.33)2.64(0.27)4.49(2.19)Weight3.50(2.14)9.32(3.35) 19.73(7.96) 25.42(6.3 8)Horizontal multiplier (HM)0.65(0.16) 0.65(0.21)0.61(0.24)0.56(0.15)Vertical multiplier (VM)0.87(0.07) 0.93(0.06)0.80(0.25)0.87(0.09)Distance multiplier (DM)0.91(0.07)0.91(0.03) 0.92(0.07)0.94(0.07)Asymmetric multiplier0.86(0.06) 0.92(0.07) 0.92(0.08) 0.89(0.07)(AM)Coupling multiplier0.92(0.03) 0.90(0.01) 0.92(0.04) 0.92(0.03)GIII. 3year, by Lifting Index (LI) CategoryLifting Index CategoryDemographicVariable03No. of workers63495467% Pain in the neck63.6 (21)19.0(4)18.2(4)16.7(6)% Pain in the lower back12.1(4)47.6(10)59.1(13)75(27)% Pain in the upper back09.5(2)18.2(4)8.3(3)% Pain in the hips/upper legs009.1(2)38.9(14)% Pain in the knees/lower legs00022.2(8)% Pain in the ankles/feet0000% Pain in the shoulders54.5(18)33.3(7)40.9(9)30.6(11)% Pain in the elbows/forearms27.3(9)23.8(5)18.2(4)8.3(3)% Pain in the wrists /hands0000% Pain in the fingers.0000% Workers missed work due toback pain from repeated activities04.8(1)36.4(8)58.3(21)in the last 12months © 2013 Global Journals Inc. (US) © 2013 Global Journals Inc. (US) Manual Lifting Task Methods and Low Back Pain among Construction Workers in the Southwestern Nigeria ## Appendix Where H= horizontal location of hands from midpoint between the ankles; measure at the origin and the destination of the lift (cm) V = vertical location of the hands from the floor; measured at the origin and destination of the lift (cm) D = vertical travel distance between the origin and the destination of the lift (cm) A = angle of asymmetric-angular displacement of the load from the sagittal plane; measure at the origin and destination of the lift (degree) F = average frequency rate of lifting measured in lift/min Duration is defined to be: ?1 hour: ?2 * System Dynamics Approach for Managing Magnitude and Risk Factors of Injuries in a Manufacturing Industry HAAjimotokan Match Seminar Report, Dept. of Mechanical Engineering 2008 Ladoke Akintola University of Technology * Back Injuries at Work and Your Office Chair Available from Articlesbase * Manual Material Handling MMAyoub PGDampsey WKarwowski Solvendy, G. 1997 * Handbook of Human factors and Ergonomics * Assessing Workrelated upper limb Disorders in a brick-making factory GBasra JOCrawford Contemporary Ergonomics. Taylor & Francis SARobertson London 1995 * DBChafing BAnderssong Occupational Biomechanics New York John Wiley 1991 2nd ed * Handling building blocks. Published by Health and Safety Commission. Construction sheet No Construction Industry Advisory Committee (CONIAC) 1993 * Safe Work Australia" Available from www. safeworkaustralia.gov 2012 Construction Work Code of Practice (CWCP) * Injuries and ill health caused by handling in the food and drink industries SafetyHealth Executive Food Information Sheet 23 2000 * Safer Construction: the development of a guide to best practice LHelen BNick WRon JDavid FTim Third International Conference of the Cooperative Research Centre (CRC) for Construction Innovation Gold Coast, Australia 2008 * Maximum permissible weight to be carried by one worker 1964 International Labour Office (ILO) * Available from www.worldcat.org/.../ maxmum-permissible-weight-to-be-car Geneva * An Ergonomics Process for the and use of Research Animals. Institute for JKerst Laboratory Animal Research Journal 44 1 2003 * Analysis and improvement of work postures in the building industry: application of the computerized OWAS method PKivi MMattila Applied Ergonomics 22 1991 * Standardised Nordic questionnaires for the analysis of musculoskeletal symptoms. Applied Ergonomics LKuorinka BJohnsson AKilo 1987 18 * Safe Manual Handling of Bariatric/Heavyweights Patients Policy. Available from www.tamesidehospital.nhs.uk/.../Safe Manual Handling of Bariatric Patients Policy Manual Handling Operations Regulations (MHOR). 1992 (online) Accessed 09-04-2011 * National Institute for Occupational Safety and Health (NIOSH). 1981. Work Practices Guide for Manual Lifting (WPG Technical Report * Department of Health and Human Services, National Institute for Occupation US * Back disorders and non-neutral trunk postures of automobile assembly workers LPunnett LJFine WMKeyserling GHerrin DBChaffin Scandinavian Journal of Work 17 1991 Environment and Health * Safety and Health Administration (OSHA) Draft ergonomics requirements. Feature Articles -ISHN Article tools 1999 * The Design of Manual Material Handling Tasks SHSnook Ergonomics 1978 * Construction Site and Building Site Accident Compensation Claims Thompsons Solicitor (TS). 2013 * Revised NIOSH equation for the design and evaluation of Manual lifting tasks TRWaters VPutz-Anderson AGarg LJFine Ergonomics 36 1993 * Applications manual for the revised NIOSH Lifting Equation. Publication no. 94-110 TRWaters VPuts-Anderson AGag 1994 DHHS (NIOSH Cincinnati, OH * Safe work method statement for demolition work Available from Www.workcover.nsw.gov.au. Accessed 2011 Work Health and Safety Regulation