A Direct-Reading Inhalable Particle Sizer with Elemental Composition Analyzer

Colorado State University, Fort Collins CO

Investigators

Abstract

Project Summary Inhalation of metal particles poses a significant hazard in the workplace. The deleterious effects of particulate metal exposure at high concentrations have been well documented in the literature. Metals that are accepted as carcinogens include chromium, nickel, beryllium, cadmium, arsenic, and silicon. For other metals such as lead, titanium, iron, and cobalt, the association between exposure and cancer is less clear, although there are other adverse health effects. For example, epidemiological studies have documented significant associations between exposure to welding fumes and diseases such as pneumonia, sidrosis, and neurological disorders such as Parkinsonism. Exposure to beryllium, in particular, remains a significant occupational hazard since exposure to even small amounts is associated with beryllium sensitization which can lead to chronic beryllium disease. State-of-the-art sampling methods for particulate metals and inhalable particles rely on time-integrated filter samples which require laboratory analysis after sampling. Such measurements provide minimal temporal or spatial resolution of the exposure and are slow (days to weeks) and costly (typically several hundred for ICP- OES analysis per sample). Occupational exposure monitoring for particulate metals rarely occurs due to high cost and effort associated with exposure monitoring. Measurement capabilities for counting and sizing particles between 20 and 100 µm in real-time are limited. Instruments capable of real-time measurements of both chemical composition and particle size, as is needed to more fully understand health effects, are even more limited. There are two specific aims to this project. The first aim develops and integrates laser-induced breakdown spectroscopy (LIBS) into our existing particle sizing instrument, the Direct-Reading Inhalable Particle Sizer (DRIPS). This aim assesses the plasma characteristics, optimizes the triggering system and particle detection rate, and develops calibration curves. A field testable prototype real-time DRIPS with Elemental Composition Analyzer (DRIPS-ECA) will be built. The second aim evaluates the calibration curves in response to alloys and develops semi-empirical models to determine metal concentration. The second aim also compares the DRIPS- ECA performance to traditional filter samples (analyzed with SEM-EDS) in a field setting.