Patterns of VOC and BTEX concentration in ambient air around industrial sources in Daegu, Korea.

Patterns of VOC and BTEX (Benzene, Toluene, Ethylvenzene, and Xylene) distribution at industrial emission sources, proximal residential areas of industrial estates, and ambient air were studied in Daegu, Korea. Daytime and night-time sampling was done at 12 sites and 9 emission sources to provide samples for analyses, using the TO-14 method. Measured BTEX component ratios B/T, T/EB, T/X and EB/X in ambient air were found to be 2.6 g, 11.3 g, 1.0 g and 1.2 g in the residential area; 2.2 g, 11.0 g, 1.0 g and 1.6 g in the commercial area; and 1.0 g, 14.9 g, 1.0 g and 1.3 g in the industrial area. The significant difference observed between the ratios for the residential and commercial areas implies that the two areas have different emission sources. This is also indicated by the significant differences observed between daytime and nighttime BTEX concentrations. Toluene and xylene were detected at very high concentrations, at the sampling sites. This pattern reflects the type of industrial processes and materials that are managed at the emission sources, as well as topographic/climatic factors that impact upon pollutant transport processes in the atmosphere. The BTEX distribution pattern in Daegu is observed to be similar to that of several Asian cities, particularly Hong Kong. These results are useful in the design of emission source control measures for VOCs and BTEX in Daegu.