Identification and quantification of volatile organic compounds in the urban atmosphere of Houston, Texas

Volatile organic compounds (VOCs) in the atmosphere are a major cause of urban air pollution. This is especially true in urban areas where industrialization has led to the emission of a large number of anthropogenic VOCs. These VOCs are a principal component in atmospheric reactions that form ozone and other photochemical oxidants. Many of these VOCs are also hazardous air pollutants that can cause adverse health effects in humans. Due to their potential risk to public health, interest in identifying and quantitating VOCs in the atmosphere has increased over the last several decades. Research has concentrated on the urban levels of VOCs due to the known and suspected carcinogenic nature of some of these compounds.; The objectives of this research were to identify and quantitate VOC concentrations in urban residential areas where schools are located less than two miles from facilities that emit large amounts of air toxins, to compare ambient air in areas far away from these types of facilities, and to characterize the distribution of these compounds throughout the greater Houston region.; Ambient air samples were collected from five locations in Harris County, Texas. 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 eight-hour period from December 2002 to March 2003. The samples were collected in six-liter stainless steel silonite-coated canisters and analyzed using a modified version of EPA Method TO-14. A total of 56 compounds were quantitated using a mass spectrometer-computer system coupled to a capillary column. Classes of compounds detected during this study consist of 18 alkanes, 14 oxygenated, 6 alkenes, 6 nitrogenated, 6 aromatic, 4 halogenated, and 2 sulfur compounds.; It was determined that the sites most heavily affected were those in close proximity to industrial facilities, such as the MacArthur and Woodland Acres sites. These sites had higher total and average VOC concentrations during both sampling campaigns. The site furthest away from all industrial facilities was least impacted by VOC concentrations. Still, residents and children in all areas sampled were potentially exposed to many toxic pollutants, in the ambient air, that are results of industrial emissions. (Abstract shortened by UMI.)...