narrower concept accident frequency Concept age structure Concept aptitude test Concept economic population Concept efficiency Concept employment protection Concept ergonomics Concept fatigue Concept health Concept increase in efficiency Concept industrial accident Concept industrial medicine Concept industrial safety Concept injury to health Concept job Concept labour Concept limit of performance Concept performance schedule Concept place of work Concept safety requirement Concept social medicine Concept work engineering Concept work flow Concept working climate Concept working condition Concept working time Concept workplace layout Concept