Construction of a musculoskeletal job-exposure matrix in Korea

Musculoskeletal disorders (MSDs) are a major occupational health issue in Korea; however, a standardized job-exposure matrix (JEM) has not been established. This study aimed to develop an MSD-specific JEM using data from the Korean Working Conditions Survey (KWCS) to evaluate the exposure time proportion by job category and body segment.

Data from the 2nd to 6th KWCS (2006-2020), covering 210,500 workers, were analyzed. The jobs of the subjects were reclassified based on the unit groups of the 7th Korean Standard Classification of Occupations. Exposure time proportion for key MSD risk factors-repetitive movements, awkward postures, heavy lifting, and prolonged standing-was categorized as high, moderate, or low based on self-reported responses. Validity was assessed through expert review and statistical analysis, including Cohen's kappa coefficients and logistic regression.

Duration-based exposure to musculoskeletal (MS) risk factors was estimated for each occupation. The JEM classified exposure time proportion for three body regions: upper extremity and neck, lower back, and lower extremity. Expert review showed high agreement for the upper extremity and neck and for the lower back (kappa > 0.8), whereas agreement was lower for the lower extremity. Logistic regression analysis indicated an exposure-response relationship between JEM-derived exposure time proportion and MS symptoms for the upper extremity and neck and the lower back.

This study developed Korea's first MS-specific JEM, providing a standardized framework for occupational MSD risk assessment. The JEM demonstrated strong validity for most body regions and can be a valuable tool for research, workplace risk evaluation, and policy development. Further refinements incorporating detailed job classifications and ergonomic factors are recommended to enhance its applicability.