AMBIENT PM4 CRYSTALLINE SILICA MEASUREMENT TECHNIQUE FOR FENCELINE SAMPLING AT FRAC SAND-PRODUCING FACILITIES AND IN WISCONSIN

The rapid expansion of frac sand producing facilities in the Upper Midwest has raised community concerns regarding exposure to crystalline silica. Air Control Techniques, P.C. has developed a sensitive sampling method for measuring PM4 crystalline silica. This method is based on EPA reference method PM2.5 samplers adjusted to collect PM4 particulate matter, which is then analyzed using NIOSH 7500 X-Ray diffraction to quantify the crystalline silica content. The limit of quantification is 0.30 micrograms PM4 crystalline silica per cubic meter—a value that is 10% of chronic reference exposure limits. This paper emphasizes the characteristics and performance of this new method in measuring PM4 crystalline silica at low ambient concentrations. The need for additional data to evaluate regional variability in ambient PM4 crystalline silica levels is also discussed.