Determining the Spatial Variability of Personal Sampler Inlet Locations

Abstract

This article examines the spatial variability of dust concentrations within a coal miner's breathing zone and the impact of sampling location at the cap lamp, nose, and lapel. Tests were conducted in the National Institute for Safety and Health Pittsburgh Research Laboratory full-scale, continuous miner gallery using three prototype personal dust monitors (PDM). The dust masses detected by the PDMs were used to calculate the percentage difference of dust mass between the cap lamp and the nose and between the lapel and the nose. The calculated percentage differences of the masses ranged from plus 12% to minus 25%. Breathing zone tests were also conducted in four underground coal mines using the torso of a mannequin to simulate a miner. Coal mine dust was sampled with multi-cyclone sampling cans mounted directly in front of the mannequin near the cap lamp, nose, and lapel. These four coal mine tests found that the spatial variability of dust levels and imprecision of the current personal sampler is a greater influence than the sampler location within the breathing zone. However, a one-sample t-test of this data did find that the overall mean value of the cap lamp/nose ratio was not significantly different than 1 (p-value = 0.21). However, when applied to the overall mean value of the lapel/nose ratio there was a significant difference from 1 (p-value < .0001). This finding is important because the lapel has always been the sampling location for coal mine dust samples. But these results suggest that the cap location is slightly more indicative of what is breathed through the nose area.

Evaluation of a Wearable Monitor for Measuring Real-Time Diesel Particulate Matter Concentrations in Several Underground Mines

“…In fact, spatial variability can lead to measurement biases of over 20%. (25,26) Therefore, in this study, the Airtec and NIOSH method 5040 results were compared using a method that takes spatial variability into account. The bias between the Airtec and NIOSH method 5040 and the percent difference between duplicate NIOSH method 5040 samples (randomly chosen from the triplicate samples) were compared.…”

Gaseous Contaminant Distribution in the Breathing Zone

“…The term "calm" used throughout this paper refers to a condition without external wind as compared to the previous field and wind tunnel studies [2][3][4][5][6] . Ethanol was used as a representative organic solvent.…”

“…However, some doubts have been raised about this assumption. Several studies have mentioned that the concentration in the breathing zone can vary when the worker is close to the contaminant source [2][3][4][5][6] . Bull et al 2) showed that test aerosol concentrations at the upper parts of the body tend to be higher than the concentrations at the lower parts.…”

“…Guffey et al used a 60%-sized mannequin in a wind tunnel, and reported that the tracer gas concentration at the chest averaged about 2.9 times the concentration at the nose 4) . Vinson et al 5) and Liden et al reported the heterogeneous distribution of dust concentrations in the breathing zone 6) . Based on these previous studies, the author aimed to evaluate the gaseous contaminant exposure of a stationary worker in a controlled laboratory atmosphere.…”

Auxiliary ventilation in mining roadways driven with roadheaders: Validated CFD modelling of dust behaviour

“…When quartz particles are present in the coal dust, additional restrictions are applied (McPherson, 1993;Vinson et al, 2007).…”