Leshan Kimbrough - Academia.edu (original) (raw)
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Chaudhary Charan Singh Haryana Agricultural University - Hisar (INDIA)
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Papers by Leshan Kimbrough
International Journal of Occupational Hygiene, 2022
The jarless cyclone calibration method is an appealing approach because it removes the need for c... more The jarless cyclone calibration method is an appealing approach because it removes the need for calibration adapters and eliminates potential sources of error that result from poor or inconsistent seals in calibration adapters or calibration jar lids. The aim of this study was to perform a detailed review of the jarless calibration method by (1) examining the rationale behind the initial pressure drop range specified by the method and (2) evaluating the accuracy of the method in contrast to flow rate measurements in a well-controlled, jar protocol. Four types of respirable cyclones and two filter brands with samples from three separate production lots were considered as components of the sampling trains under consideration. Volumetric flow rate and pressure drop were measured under controlled conditions in a cylindrical jar designed for these determinations. The initial challenge pressure range evaluated in this study was modified based on cyclone type. The measured pressure drop fe...
International journal of occupational hygiene, 2019
The measure of volumetric flow rate is utilized to calculate sampling volume and airborne concent... more The measure of volumetric flow rate is utilized to calculate sampling volume and airborne concentration in integrated air sampling. Consequently, calibration of the sampling train to verify volumetric flow rate is critical. The relation between sampler pressure drop and volumetric flow rate was studied in support of using the former rather than the latter for the calibration of sampling trains. Four types of respirable cyclones, two filter brands with membrane samples of the same and different lots of production, and two personal pump types were considered as components of the sampling trains under consideration. Volumetric flow rate and pressure drop were measured under controlled conditions in a cylindrical jar designed for these determinations. For all the configurations considered, the relation between sampler pressure drop and standard volumetric flow rate was linear. Intra-sample selection of cyclones of the same type and pump type did not create significant differences in s...
Journal of Occupational and Environmental Hygiene, 2020
The exposure prediction component of the Control of Substances Hazardous to Health (COSHH) Essent... more The exposure prediction component of the Control of Substances Hazardous to Health (COSHH) Essentials model (paper version) was evaluated using field measurements from National Institute of Occupational Safety and Health (NIOSH) Health Hazard Evaluation (HHE) reports. Overall 757 measured exposures for 94 similar exposure groups (SEGs) were compared with the COSHH Essentials predicted exposure range (PER). The SEGs were stratified based on the magnitude of measured exposures (high, medium, or low) and physical state of the substance (vapor or particulate). The majority of measured exposures observed involved low-level exposure to vapors; thus, overall findings from the current study are limited to low-level vapor exposure scenarios. Overall, the exposure prediction component of COSHH Essentials vastly overestimated low-level exposures to vapors. This study went beyond the scope of previous studies and investigated which model components led to the overestimation. It was concluded that COSHH Essential's tendency to overestimate was due to multiple complex interactions among model components. Overall, the magnitude of overestimation seems to increase exponentially as values for predictor variables increase. This is likely due to the log-based scale used by the model to allocate concentration ranges. In addition, the current banding scheme used to allocate volatility appears to play a role in the overestimation of low-level exposures to vapors.
International Journal of Occupational Hygiene, 2022
The jarless cyclone calibration method is an appealing approach because it removes the need for c... more The jarless cyclone calibration method is an appealing approach because it removes the need for calibration adapters and eliminates potential sources of error that result from poor or inconsistent seals in calibration adapters or calibration jar lids. The aim of this study was to perform a detailed review of the jarless calibration method by (1) examining the rationale behind the initial pressure drop range specified by the method and (2) evaluating the accuracy of the method in contrast to flow rate measurements in a well-controlled, jar protocol. Four types of respirable cyclones and two filter brands with samples from three separate production lots were considered as components of the sampling trains under consideration. Volumetric flow rate and pressure drop were measured under controlled conditions in a cylindrical jar designed for these determinations. The initial challenge pressure range evaluated in this study was modified based on cyclone type. The measured pressure drop fe...
International journal of occupational hygiene, 2019
The measure of volumetric flow rate is utilized to calculate sampling volume and airborne concent... more The measure of volumetric flow rate is utilized to calculate sampling volume and airborne concentration in integrated air sampling. Consequently, calibration of the sampling train to verify volumetric flow rate is critical. The relation between sampler pressure drop and volumetric flow rate was studied in support of using the former rather than the latter for the calibration of sampling trains. Four types of respirable cyclones, two filter brands with membrane samples of the same and different lots of production, and two personal pump types were considered as components of the sampling trains under consideration. Volumetric flow rate and pressure drop were measured under controlled conditions in a cylindrical jar designed for these determinations. For all the configurations considered, the relation between sampler pressure drop and standard volumetric flow rate was linear. Intra-sample selection of cyclones of the same type and pump type did not create significant differences in s...
Journal of Occupational and Environmental Hygiene, 2020
The exposure prediction component of the Control of Substances Hazardous to Health (COSHH) Essent... more The exposure prediction component of the Control of Substances Hazardous to Health (COSHH) Essentials model (paper version) was evaluated using field measurements from National Institute of Occupational Safety and Health (NIOSH) Health Hazard Evaluation (HHE) reports. Overall 757 measured exposures for 94 similar exposure groups (SEGs) were compared with the COSHH Essentials predicted exposure range (PER). The SEGs were stratified based on the magnitude of measured exposures (high, medium, or low) and physical state of the substance (vapor or particulate). The majority of measured exposures observed involved low-level exposure to vapors; thus, overall findings from the current study are limited to low-level vapor exposure scenarios. Overall, the exposure prediction component of COSHH Essentials vastly overestimated low-level exposures to vapors. This study went beyond the scope of previous studies and investigated which model components led to the overestimation. It was concluded that COSHH Essential's tendency to overestimate was due to multiple complex interactions among model components. Overall, the magnitude of overestimation seems to increase exponentially as values for predictor variables increase. This is likely due to the log-based scale used by the model to allocate concentration ranges. In addition, the current banding scheme used to allocate volatility appears to play a role in the overestimation of low-level exposures to vapors.