Abstract
Ambient respirable crystalline silica air quality is of concern to many communities near mineral processing facilities and to regulatory agencies serving these communities. Accurate air quality data are needed to compare measured respirable crystalline silica concentrations at the fencelines of mineral processing facilities with the published health effect guideline published by the California Office of Health Hazard Assessment (OEHHA). This article is a compilation and evaluation of air quality studies around a diverse set of nineteen sand producing facilities. The respirable crystalline silica air quality data compiled by Air Control Techniques, P.C. and most of the data compiled by other researchers cited in this article have been measured using EPA Reference Method samplers adjusted for respirable crystalline silica sampling and NIOSH Method 7500 X-ray diffraction analyses. The authors conclude that (1) the ambient concentrations in the diverse set of mineral processing facilities were consistently lower than the 3.0 microgram per cubic meter chronic reference exposure level (REL) adopted by OEHHA, (2) upwind-to-downwind fenceline concentration differences were small, and (3) the fenceline t concentrations were often at background concentration levels. The authors recommend additional sampling studies to better characterize background concentrations of ambient respirable crystalline silica.
Highlights
To provide a more comprehensive set of air quality data, this paper summarizes ambient respirable crystalline silica concentration measurements over long time periods at numerous additional mineral facilities having diverse process equipment, production capacities, and surrounding terrain features that could potentially affect dispersion of fugitive dust emissions
This paper summarizes PM4 respirable crystalline silica concentrations at a wide variety of mineral producing facilities
The large majority of the data were obtained in strict accordance with EPA reference method procedures and quality assurance procedures. These studies help to characterize the range of ambient concentrations or PM4 crystalline silica that exists in a broad sector of mineral industry sources
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. OEHHA based this guideline on industrial hygiene health effects studies conducted with PM4 crystalline silica personal occupational exposure samplers In both the occupational hygiene studies and the air quality studies addressed in this article, PM4 is defined as particulate matter having aerodynamic sizes equal to or less than 4 micrometers as measured in accordance with NIOSH Method 0600 or equivalent procedures. Peters et al [12] published ambient monitoring data at seventeen residences located within 800 m of frac sand quarries in western Wisconsin and found ambient respirable crystalline silica concentrations below the OEHHA REL in samples obtained during 48 h sampling periods. To provide a more comprehensive set of air quality data, this paper summarizes ambient respirable crystalline silica concentration measurements over long time periods at numerous additional mineral facilities having diverse process equipment, production capacities, and surrounding terrain features that could potentially affect dispersion of fugitive dust emissions. Acronyms and definitions of terms used are listed at the end of this article
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