Hazard mapping with direct reading instruments from facilities with high and low temporal variability

Abstract

The purpose of this study was to develop novel sampling techniques employing relatively lower-cost direct-reading instruments (DRIs, instruments that report hazard intensity at near real-time resolution) for hazard mapping. Normally, personal sampling equipment worn by workers is used to determine personal exposure (time-weighted average) to a hazard for comparison with an occupational exposure limit (OEL). However, time-weighted average methods give the industrial hygienists (IH) no information on the spatial or temporal variability of the exposures. Hazard maps have been suggested as a way to represent spatial variability in hazard intensity displayed as contours of hazard intensity on the facility floor plan. Traditionally, expensive direct-reading instruments (e.g., sound level meters) are used to create these hazard maps by collecting numerous individual measurements over a single-traverse of a workspace. These instruments fail to determine the temporal variability in exposures through the workplace and as such, may miss important, but transient exposures. To overcome these limitations, we proposed that we could enhance both the spatial and temporal resolution, compared to single traverse sampling strategies, by deploying lower-cost static personal monitors that captured temporal variability distributed throughout the facility and roving personal monitors that capture spatial variability over multiple traverses throughout whole work shifts. These novel sampling techniques were evaluated at two locations with different temporal variabilities: a Plastic Manufacturing Facility (PMF), having low temporal variability, and the Engines and Energy Conversion Laboratory (EECL) at Colorado State University, having high temporal variability. The goals of the sampling at these locations were three-fold. First, we wished to determine if hazards maps generated with different sampling techniques were similar, depending on the temporal variability. Relative similarity was assessed by comparison of overall mean squared difference between maps and percent differences from location-specific interpolated values between hazard maps. Second, since the new sampling technique was not validated, we wanted to determine if measurements taken from personal noise dosimeters, operated as static or roving monitors, and a sound level meter (SLM) exceeded instrument accuracy, when collected at the same time and in close spatial proximity. Third, in the course of these studies, several occupational hazard assessments were also carried out at these locations. These assessments included determination of effective hearing protector usage, characterization of noise, vibration, and diesel exhaust hazards, and evaluation of noise and diesel exhaust engineering controls.