Challenge with a Personal Cascade Impactor Sampler in a Silicon Metal Smelter

Balázs Berlinger,Torunn K Ervik,Nathalie Benker,Merete D Bugge,Konrad Kandler,Bente Ulvestad,Dag G Ellingsen

doi:10.4209/aaqr.200577

Abstract

ABSTRACT Cascade impactors are useful tools in the measurement of particle size mass distribution of workplace aerosols. The application of cascade impactors, however, is sometimes challenging. Personal aerosol samples were collected by Sioutas cascade impactors and respirable cyclones in parallel in a silicon (Si) metal smelter to investigate the different particulate matter (PM) fractions. In a second campaign, nine new air samples were collected with the Sioutas personal cascade impactors using stationary sampling. It was found that wall deposition was substantial in the upper stages of the Sioutas cascade impactors, which meant that quite often more PM was deposited on the inner walls of the impactor than on the filter substrates. At the same time, wall deposition did most probably not affect the collection of the finest particles (< 0.25 µm). Besides wall deposition of the particles, the effect of high PM concentration on the impactor performance, particle bouncing and blow off, high particle mass loading and impact fragmentation of the particle agglomerates were considered for explaining the malfunctioning of the Sioutas impactors in the Si metal smelter. Furthermore, concentrations of the finest PM fraction (< 0.25 µm) and respirable fraction both collected by personal sampling are reported and discussed in the paper.

Highlights

The health effects in the respiratory tract resulting from the inhaled and deposited particulate matter (PM) depend on the dose received, the site of deposition and the bodys response to the deposited particles (Volkwein et al, 2011)
The present paper describes the challenges with the applied personal cascade impactor samplers in this environment, discusses the possible reasons for the malfunction of the impactors and presents selected results largely unaffected from error
Concentrations of the different PM size fractions collected by the personal impactors were compared to concentrations of the respirable fraction collected in parallel by the personal respirable cyclones as the first step of the evaluation

Summary

Introduction

The health effects in the respiratory tract resulting from the inhaled and deposited particulate matter (PM) depend on the dose received, the site of deposition and the bodys response to the deposited particles (Volkwein et al, 2011). An important aim of workplace air measurement is to estimate the effective dose of PM delivered to the lungs. Aerosol particle size is one of the key factors that determine where and whether particles will deposit in the respiratory tract (ICRP, 1994; Bartley and Vincent, 2011). From most conventional workplace aerosol measurements information on particle size distribution is not available. Cascade impactors can be useful tools to assess the mass size distribution. In spite of the importance of the particle size distribution in workplace aerosol characterisation, cascade impactors are not very widespread for personal sampling. Nieuwenhuijsen et al (1998) applied Sierra Marple 294 cascade impactors to measure personal dust exposure levels and the particle size distribution of the dust occurring during various agricultural operations in California. There exist a few alternatives and an overview of published studies follows. Nieuwenhuijsen et al (1998) applied Sierra Marple 294 cascade impactors to measure personal dust exposure levels and the particle size distribution of the dust occurring during various agricultural operations in California. Cohen and Powers (2000) investigated the exposure to copper and zinc in a nonferrous foundry

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