SPATIAL AND TEMPORAL ASSESSMENT OF POINT SOURCE RESPIRABLE ALPHA QUARTZ IN NEW BRAUNFELS, TEXAS, U.S.A.

Abstract

Respirable α-quartz fugitive aerosols produced from aggregate production operations (APOs) within limestone bedrock strata have been associated with increased adverse health effects in workers and surrounding populations. Efforts to monitor silicate mineral constituents sourced from these lithologic units have increased to better characterize the significant amount of α-quartz dust present. This study aims to speciate and relatively quantify the α-quartz content present in 36 ambient dust samples collected within the perimeter of a major APO in New Braunfels, Texas, using Fourier Transformation Infrared (FTIR) spectroscopy and scanning electron microscopy with energy dispersive X-ray (SEM-EDX). While FTIR and SEM-EDX have been used to estimate quantities of emissions from a single potential point source, few studies compare results between the methods. Understanding the chemical properties of the observed species is essential to understanding the effect on air quality across the region and the potential effects it has on population health. While both methods contained uncertainties, concentrations for multiple samples were on average 2.5 times higher than permissible exposure limits. Further action should be taken to capture fugitive dust to prevent these high levels from affecting the health of workers and citizens.