Task-based good work practice control guidance intervention to reduce respirable crystalline silica exposures in small-scale demolition operations.

摘要

Changes in work practices and dust exposures following training were evaluated among workers engaged in small-scale demolition of concrete and masonry structures/buildings. One-page employee and multiple-page supervisor task-based good work practice control guidance sheets (TB-GWP-CGSs) were adapted from existing documents and workers were trained in use of the information. Interactive hands-on training was delivered to 26 workers from two demolition crews, and then evaluated using a chain of evidence with seven levels. A pre-and-post walkthrough survey was used by trained observers to document work practices, and NIOSH 0600 and NIOSH 7500 methods were used to assess silica dust exposure levels.;Worker feedback indicated that the training was effective and useful. Workers acquired knowledge (84% increase, p0.001) and mastered skills in the application of TB-GWP-CGSs. The difference of proportions between use of work practice components before and after the intervention was statistically significant (p0.005). The alpha quartz percent ranged from 18 to 40% in six bulk samples collected from five different demolition sites. The percent reduction in dust exposure ranged from 40 to 78% after the intervention. The maximum silica exposure measured in a crew was reduced from 18 to 85% after the intervention. Small-sample size and results below the limit of detection prevented additional statistical inference.;The intervention was successfully developed and implemented. Following training substantial changes in work practices were observed, including preplanning, use of wet methods, natural ventilation and end-of-task review. Consistency in inter-observer ratings and observations by the trained observers suggest good reliability and validity of the walkthrough survey of the instruments. Respirable dust and respirable quartz exposure levels indicated reduction following training. The approach used in this study demonstrated the short-term benefit of training in changing work practices. Work organization limited the collection of task-based dust measurements. Also, only one of the two crews returned to the same worksite after training.;Future studies should include additional air sampling over a longer follow-up period to improve exposure estimation. A better understanding of work organization will maximize evaluation of task-based exposure controls.