Minnesota Taconite Workers Health Study: Environmental Study of Airborne Particulate Matter - Development of Standard Operating Procedures for Particle Collection and Gravimetric Analysis

Abstract

Since late 2008, the Natural Resources Research Institute’s overall participation in the Minnesota Taconite Workers Health Study has been focused on the characterization of aerosol particulate matter on the Mesabi Iron Range in northeastern Minnesota. This study is formally known as the “Environmental Study of Airborne Particulates,” and it is one of five studies being conducted by the University of Minnesota School of Public Health and the Natural Resources Research Institute. An initial standard operating procedure (SOP) for particle sampling associated with the “Environmental Study of Airborne Particulates” was first developed through planning and collaboration with aerosol scientists at the University of Minnesota, Department of Mechanical Engineering. Since then, through additional experimentation and revisions, the original SOP sampling document has evolved into the comprehensive narrative that it is at present. This current document outlines a history of evolving in-house experiments and observations that ultimately resulted in the development of the SOP adopted by and practiced in the “Environmental Study of Airborne Particulates.” Equipment utilized in sample collection included the Micro-Orifice Uniform Deposition Impactor (MOUDI; Marple et al., 1991), a device which collects size-fractionated samples of particulate matter with aerodynamic diameters ranging from 30.0 to 0.056 microns, and a final filter that collects particles with aerodynamic diameters less than 0.056 microns. As well, a Total Filter Sampler (TFS), which collects all size fractions of particulate matter on a single substrate, was utilized so that particulate could be evaluated using Minnesota Department of Health analytical methods (Minnesota Department of Health Method 852). Results from the MOUDI sampling allow particulate matter (PM) to be classified into specific size classifications including: PM1, PM2.5 and PM10, which are important in assessing potential air quality measurements. As well, samples collected using the MOUDI sampler could be further evaluated using a wide variety of physical and chemical methods (for example, analysis using transmission and scanning electron microscopy, chemical analysis using proton induced X-ray emission analysis (PIXE)).