Characterization of BTEX species at Texas Commission on Environmental Quality (TCEQ) Continuous Ambient Monitoring Station (CAMS) sites in Houston, Texas, USA during 2018

Abstract

Volatile Organic Compounds (VOCs) in the atmosphere negatively impact human and environmental health. Various sources of VOCs include gasoline evaporation, solvent usage, traffic, etc. A dataset 1-year (2018) consisting of BTEX (benzene, toluene, ethylbenzene, and m, p, and o-xylenes) concentrations in Houston, Texas, was analyzed to understand the spatial trends and sources of BTEX in the region. This study assesses 24-hour data concentrations from the Continuous Ambient Monitoring Station (CAMS) operated by the TCEQ Texas Commission on Environmental Quality (TCEQ) in Houston. Spatial variations of the BTEX species across the various TCEQ CAMS sites were determined using multiple statistical analyses, including Coefficients of Divergence (COD), Spearman’s correlation coefficient, and ANOVA Tukey’s test, while the BTEX interspecies ratios were calculated for further inter- and intra-urban exposure characterization. Ozone Forming Potential (OFP) was also calculated to analyze the role of VOCs in the formation of tropospheric ozone and to understand the role of VOCs in OFP in multiple seasons. OFP was higher in colder months than in other seasons of the year. Toluene exhibited greater concentrations with emission sources related to vehicular traffic emissions. The sites near the cluster of refineries were observed to have higher BTEX concentrations than others in Houston, Texas. These findings could help formulate targeted emission reduction strategies, for overall VOC levels in Houston, Texas.