Safe lifting ergonomics program for truck-loaders in Nigerian block making industries: A multi-site case study with qualitative and econometric analyses

An ergonomic method of lifting (EML) was introduced to truck loaders in the South-western Nigeria blocks-making industry (BMI). The aim was to measure the ergonomics and economic benefits. With 125 workers and 30 managers from 25 BMI, workers' self-adopted un-ergonomics methods of lifting (UML) were assessed at baseline. Workers then received ergonomics training. Actual lifting time, pace/time losses, task quality were measured pre and post-intervention in addition to a cost evaluation, at the 7th, 30th and 60th days into EML implementation, involving return-on-training-investment (ROTI) and ergonomics training-yield index (ErgoT-YI). Job demands and workers/managers' opinions about UML and EML were rated through questionnaires. Under UML, 76% of the workers were frequently absent from work due to lifting-related injuries of which 84% complained of fatigue, back and shoulder pains. Performance under UML was 64% and rated 48% after EML implementation. The average actual productive time improved from 95% (UML) to 97% (EML). ROTIEML was better than ROTIUML by 18.5%. The calculated ErgoT-YI was 1.18 after 7days post-intervention and increased to 18.62 after 60 days, making EML superior to UML. An independent samples t-test showed a reduction in product/material wastage with EML (t = 7.900; p