Ergonomic hazards are known to be the leading cause of disability in building construction industries around the world

Ergonomic hazards are known to be the leading cause of disability in building construction industries around the world(1). As a result, the international community has established policies and guidelines as the weapons of fighting musculoskeletal disorders among construction industry and other sectors. Ergonomist define the term ergonomic as “an applied science that co-ordinates the design of devices, systems and physical working conditions with the capacities and requirements of the workers”(2). Improper work design which is known as poor ergonomic design, expose workers to soft tissue injuries called musculoskeletal disorders. Musculoskeletal disorders (MSDs) are soft tissue (muscles, ligament, tendons) injuries that are caused due to exposure to ergonomic risk factors(3). There are several common ergonomic risk factors that predispose building construction workers to MSDs, which include the following; awkward posture when plastering or other building task, using force when puling or pushing objects, repetitive motion when laying bricks, exposure to vibration for long hours especially when drilling or using jackhammers, cold temperature (during winter) or hot temperature (in summer), working on an uneven or mud surface, contact stress when working with forearm or wrist against the edge of objects or the work counter and static loading when working on the same posture for a prolonged time (2).
Literature indicate that over 38% musculoskeletal disorders prevalence has been recorded annually among building construction workers in Europe (4). While in United State of America recorded over 49% musculoskeletal disorders prevalence during a period of two years, in 2011 to 2012(5). Africa recorded the highest number of MSDs prevalence of 76 per 100 000 building construction workers annually(6). As a result, in Sub-Saharan Africa the prevalence of MSD stand at 21 per 100,000 building construction workers and the disability rate at 16 per 100 000 workers. This shows that over 54 million permanent disabilities are recorded annually and 42 million work-related musculoskeletal injuries occur, which lead to at least three or more days’ absence from work(7). As a result, poor ergonomically designs of construction workstation, equipment and the entire construction sites contribute 5% accidents and 0.8% fatalities due to fatigue and lack of concentrations among workers(8). In Namibia, 36 per 1000 MSDs prevalence of the total population was recorded from 2008 to 2011(9). However, due to inconclusive figures on MSDs prevalence in Namibia context on specific workers profession or category, academic research still on high demand. These might trigger further research to determine specific figure of each profession or work category at risk of musculoskeletal disorders in the country, in this case building construction workers.
The building construction industry is the largest employment sector, creating over a billion employments worldwide(10). Building construction workers are categorised in different trades (plasters, concrete mixer, labourers, electrician, riggers and plumbers) which means that they performed different task and risk exposures vary. As result, different activities have different ergonomic risk factors as well as different effect (MSDs injuries or disability)(11).
Building construction workers are exposed by different health hazards at sites, which make them vulnerable to three main occupational hazards namely, chemical, ergonomic and physical hazards. These may include chemicals from paints, noise from equipment and construction vehicles, dust from cement and movement of construction vehicles, awkward posture, heavy lifting of objects, working long hours without sufficient breaks and working on uneven platforms(12). Moreover, exposure to such hazards lead to musculoskeletal disorders, diseases and accidents or even death. Namibia recorded 38 major accidents and 18 fatalities for the past five years(from 2012 to 2017) as result of occupational hazards(13). Furthermore, ergonomic hazards at building construction sites pose a significant health risk to workers which lead to falling due to muscles fatigue and permanent disability, as result of MSDs.

Namibia boasts big construction companies and small medium enterprises which undertake a range of complex and simple construction projects. The researcher managed to select four building construction companies which where operational during the undertaking of the research project. It is worth noting that the study was conducted during a period of severe economic constraints in the country’s construction industry. The company where selected using a stratified simple random sampling. The four selected building construction companies were Namib Construction, Madigaga Investment Close Corporation, Ompeke Construction Company and Xui-li Construction Company. Namib Construction Company is one of the biggest construction companies in Namibia, which has been operating before the country gain its independence in 1990. The company employs over 1000 employees, which include bricklayers, engineers, administrators, electrician, carpenters, steel workers, riggers, crane operators, etc. However, not all 1000 employees where working at a construction site which was selected for the research project. Namib Construction Company has been appointed to upgrade and extend one of the largest shopping mall (Whenill Park), located in the heart of the capital city (Windhoek). The project started in November 2017 and expected to run until February 2019.
Madigaga Investment Close Corporation a Namibian born company was also selected as the study subject. The company was founded in 2005 and has been operational to date. Madigaga Construction Company is a small-to-medium enterprise company which employs 56 employees. The company was contracted to construct a warehouse at refreeze industrial park. The third company was Xui-li Construction Company which is a Chinese born Construction Company which was building an office complex at Clein Kuppe near Grove Mall. The company has been operating in Namibia since February 2014 and employed 345 workers. Ompeke Construction Company is a Small Medium Enterprise which undertakes house building projects at the vicinity of Katutura, with 123 employees. Ompeke is the Namibian born company which start its operation in 2015 and it was establish in 2011.
The study investigated the association between the MSDs and common ergonomic risk factors among building construction workers, working for company which were operational during data collection and which are registered with City of Windhoek(14).

1.3 Problem statement
Musculoskeletal injuries continue to be a major leading cause of disabilities and loss of work time in building construction industries around the world with prevalence range from 15% to 69%(15). Literature show that 95% of ergonomic risk factors lead to the development of MSDs and become a major occupational problem among many professions, of which building construction workers are most vulnerable(11). Musculoskeletal disorders among building construction workers develop due to long term exposure to the following common risk physical factors, repetitive work, awkward posture, working long hours without brakes and static force(12). This will result in to musculoskeletal injuries in deferent body region (upper, middle and lower body region).

In Namibia, about 36% MSDs prevalence of the total population was recorded for the past three years, from a hospital base survey(9). The information obtained from the report did not specify worker categories but rather the MSDs prevalence of all patients visit the hospital with such condition in the whole country, so generalization become difficult. On a contrary the information does not include people of the same work sector, and who did not visit the hospital. As result shortage of ergonomic studies still a challenge in Namibia. In South Africa the prevalence of MSDs among building construction workers stand at 25%, and this might be the same or more in Namibia due to the fact that South African construction companies are operating in Namibia(16). However, the country lacks publications of this nature, which made it difficult to make a distinctive on ergonomic and musculoskeletal disorders statistics of each specific profession from the national statistics. As result there is a need for such studies to determine the association of ergonomic risk factors and the development of MSDs among each profession in the country, in order to develop prevention measures specific for each risk factors pertaining to that profession. The Namibian Employer Federation state that, is always difficult