Measurement of Volatile Organic Compounds in the Urban Atmosphere of Harris County, Texas

Abstract

Volatile organic compounds (VOCs) are a major component of urban air pollution. It is well documented that exposure to certain types of VOCs can cause adverse health effects such as cancer, immune and neurological damage, and reproductive and endocrine disorders. Urban air samples were collected at five locations in Harris County, Texas to determine the measurement of VOCs in the ambient air of residential areas in close proximity to industrial facilities that emit toxic air pollutants into the air. Three locations used in this study were located along the Houston Ship Channel (HSC), in the heart of one of the largest petrochemical complexes in the nation. Two other sampling locations were located many miles away from the ship channel and any industrial facilities that are required to report toxic air emissions. Air samples were collected daily over an 8-h period from December 2002 to March 2003. The samples were collected in 6-L stainless steel Silonite-coated canisters and analyzed using a modified version of EPA Method TO-15. A total of 53 compounds was quantitated using a gas chromatograph mass spectrometer system coupled to a cryogenic preconcentrator. Eighteen alkanes and oxygenated compounds were identified, along with 7 alkenes and 5 aromatic compounds. Several alkanes such as butane, isobutane, 2-methyl butane, and pentane were detected at all five sites. The total VOC concentrations determined were highest at two of the industrial sites and lowest at the site farthest away from the ship channel and any industrial facilities. This study concluded that the atmosphere near Harris County's industrial complex had higher concentrations of VOCs than the atmosphere in areas farther away from the HSC. The atmosphere of areas downwind from emission sources were found to be directly affected by toxic air emissions from industrial process but not at the levels seen in areas closer to the HSC.