Adapting old methods for new trends

Abstract

PDS 65: Exposure assessment: implications for epidemiology, Exhibition Hall (PDS), Ground floor, August 27, 2019, 1:30 PM - 3:00 PM Background: There are an estimated two billion informal sector workers around the globe. There is a clear need to adapt existing methods for identifying occupational hazards to meet the needs of unregulated and unpredictable work environments where unprotected workers face substantial risk from numerous hazards. We designed and applied a method of deriving time-activity patterns using wearable cameras to characterize time-use and contemporaneous, continuous measures of personal inhalation exposure to size-specific particulate matter (PM) among workers at an informal electronic-waste (e-waste) recovery site. Methods: 142 workers at the Agbogbloshie e-waste site in Ghana wore a sampling backpack with a wearable camera and real-time particle monitor during 171 shifts. Images and PM2.5 measurements were collected each minute, along with self-reported recall of time-activity (30-minute resolution) using a diary. Collected images (N=35,588) were processed to identify activities using criteria established through worker interviews, observation and existing literature. Descriptive statistics were generated for activity types, frequency and, as proof of concept, to demonstrate the camera’s ability to detect predicted relationships between PM2.5 and e-waste tasks. A kappa statistic measured agreement between self-reported and image-based time-activity data. Results: Based on image-based time-activity patterns, workers primarily dismantle, sort/load, burn and transport e-waste materials for metal recovery with high variability in activity duration. The overall geometric mean (GM) of personal PM2.5 on-site was 60.1 µg/m3 (SD: 2.1); PM2.5 was highest during burning, sorting/loading, and dismantling (GM: 90.4, 67.6, and 67.3 µg/m3 respectively). However, PM2.5 during long periods of non-work-related activities exceeded the World Health Organization 24-hour ambient PM2.5 guideline 75% of the time. Image-derived and self-reported time-activity had poor agreement (kappa = 0.17). Conclusions: Even in complex, non-formalized work environments, wearable cameras can improve occupational exposure assessments and identify activities associated with high exposures to workplace hazards by providing a transparent source of highly resolved time-activity data.