Task-specific lead exposure during residential lead hazard reduction projects

This article describes a study of worker airborne lead exposure during residential lead hazard reduction projects. The study was performed to characterize short-term, task-specific exposures and to test an airborne lead exposure prediction equation that could assist residential lead abatement contractors in selecting engineering controls and personal protection prior to bidding on a project. A total of 224 personal air samples were collected from 16 workers employed by three contractors at 11 San Francisco Bay-area homes. Exposures ranged from <1.0 microg/m3 to 146.0 microg/m3. Although exposures were low overall (geometric mean = 4.2 microg/m3), there was considerable variability (geometric standard deviation = 4.3 microg/m3). The task-specific approach to exposure assessment used in this study was effective in revealing short-term, high exposures that would be missed during full shift sampling. The highest exposures occurred during paint scraping, demolition, and chemical stripping. Task-specific sampling was also effective in identifying tasks with low exposure potential, such as wet sanding, component removal, and clean-up. Since exposures were not significantly correlated with paint lead content or task area size, two of the variables of the prediction equation, the equation does not appear to be an effective means of predicting airborne lead exposures. Additionally, other factors such as water usage and contractor type had a significant effect on exposure levels. By controlling for these factors, exposures were significantly correlated with the third variable of the prediction equation, the proportion of paint removed from task areas. This study also demonstrates the importance of contractor specific exposure assessments, as there were significant differences in exposures between contractors, even with similar work methods and water use frequency.