AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Development of a Direct-Reading Inhalable Particle Sizer with Elemental Composition Analysis
JAMES SIPICH, John Volckens, Christian L'Orange, Azer Yalin, Kimberly Anderson, Christopher Limbach, Colorado State University
Abstract Number: 873 Working Group: Instrumentation and Methods
Abstract No technology currently exists to quantify the size and elemental composition of large (>20µm) airborne particles in real time. Such aerosols are created from manufacturing processes such as abrasive grinding and cutting; they are also present following mechanical resuspension (i.e. wind-blown dust). Exposure to large, inhalable aerosols can have a substantial detrimental impact on health. Our understanding of the behavior of such particles is limited, due in part to a lack of information about their size and elemental composition. Current methodologies for characterizing inhalable particles involve sample collection onto filter substrates that require subsequent offline analyses. These provide only time-integrated results, which further limits our ability to study the dynamic nature of aerosols. A device capable of directly measuring the size and composition of large particles would be a valuable tool for the identification and control of occupational aerosol hazards.
The objective of this work was to develop a portable, direct-reading instrument to determine the size and composition of airborne particles larger than 20μm in aerodynamic diameter. Particle size is determined by analyzing the light signals produced as a result of Mie scattering as settling particles pass through an infrared laser sheet. The current prototype device can detect and size particles from 20 to 130µm, though this detection range can be adjusted.Chemical composition of particles is established through laser induced breakdown spectroscopy (LIBS) that immediately follows the Mie scattering measurement. The LIBS process uses a pulsed laser source to form a plasma that excites the electrons in the material within the plasma. As these electrons relax, light is emitted at characteristic wavelengths that depend on the elemental composition of the analyte mass. The prototype device can perform simultaneous detection of light emitted in the 300-800nm range, sufficient for LIBS analysis of many common materials.