Spatial-seasonal variations and source identification of volatile organic compounds using passive air samplers in the metropolitan city of Seoul, South Korea

The large emission of volatile organic compounds (VOCs) is an important environmental issue in Seoul, the capital of South Korea. However, the spatial distribution of VOC emissions has not yet been clearly revealed. In this study, passive air samplers (PASs) were seasonally deployed to measure 50 VOCs at 26 urban, 4 road, and 6 background sites in Seoul. Among the target compounds, toluene (summer: 8.72 μg/m3; winter: 5.47 μg/m3), ethyl acetate (summer: 2.36 μg/m3; winter: 3.51 μg/m3), and ethylbenzene (summer: 1.72 μg/m3; winter: 0.88 μg/m3) exhibited higher mean concentrations than other compounds. Printing offices and industrial facilities seem to have strong influences on the VOC levels in the center and southwest of Seoul, respectively. Diagnostic ratios indicated that the main sources of VOCs were related to local volatilization in summer and vehicular exhaust and transport from other areas in winter. Positive matrix factorization (PMF) suggested four major sources of VOCs: residential/commercial solvents for printing and painting (Factor 1); transport from other areas (Factor 2); industrial solvents for painting, manufacturing, and cleaning (Factor 3); and gasoline/diesel vehicular exhausts (Factor 4). Factors 1 and 3 were dominant in summer, and Factors 2 and 4 were dominant in winter. In conclusion, the seasonal meteorological conditions (e.g., temperature and wind patterns) were found to play an important role in the spatial distribution of VOCs in Seoul, and solvent use was a predominant source. [Display omitted] •Passive air samplers were deployed at 36 sites in Seoul, Korea in summer and winter.•Toluene, ethyl acetate, and ethylbenzene were dominant compounds in both seasons.•The high concentrations of VOCs were observed in the center and southwest of Seoul.•The main source of VOCs in summer was the local volatilization of solvents.•Vehicular exhaust and transport from other areas were dominant in winter.