Evaluation of One- and Two-Box Models as Particle Exposure Prediction Tools at Industrial Scale.

Carla Ribalta,Keld Alstrup Jensen,Alexander Christian Østerskov Jensen,Mar Viana,Ana Sofia Fonseca,Ana López-Lilao,Eliseo Monfort

doi:10.3390/toxics9090201

Abstract

One- and two-box models have been pointed out as useful tools for modelling indoor particle exposure. However, model performance still needs further testing if they are to be implemented as trustworthy tools for exposure assessment. The objective of this work is to evaluate the performance, applicability and reproducibility of one- and two-box models on real-world industrial scenarios. A study on filling of seven materials in three filling lines with different levels of energy and mitigation strategies was used. Inhalable and respirable mass concentrations were calculated with one- and two-box models. The continuous drop and rotating drum methods were used for emission rate calculation, and ranges from a one-at-a-time methodology were applied for local exhaust ventilation efficiency and inter-zonal air flows. When using both dustiness methods, large differences were observed for modelled inhalable concentrations but not for respirable, which showed the importance to study the linkage between dustiness and processes. Higher model accuracy (ratio modelled vs. measured concentrations 0.5–5) was obtained for the two- (87%) than the one-box model (53%). Large effects on modelled concentrations were seen when local exhausts ventilation and inter-zonal variations where parametrized in the models. However, a certain degree of variation (10–20%) seems acceptable, as similar conclusions are reached.

Highlights

In occupational hygiene, there is a need to assess worker exposure for a large variety of microenvironments and materials in order to guarantee workers safety
A previously published case study where seven materials packed in three filling lines with different levels of energy and mitigation strategies applied was used [30]
Exposure concentrations were modelled in terms of inhalable and respirable mass fractions, and effects of different local exhaust ventilation (LEV) and β values were analysed

Summary

Introduction

There is a need to assess worker exposure for a large variety of microenvironments and materials in order to guarantee workers safety. In order to build trust in the use of quantitative exposure prediction models for exposure assessment and management, extensive testing against real-world cases are needed to test model performance and to understand the uncertainties related to critical parameters such as source characterization, local controls and air mixing, which are not yet fully parametrized and understood [14,15]. These determinants of exposure are often challenging to estimate in real-world scenarios [9,16,17,18]

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Conclusion