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Ambient air concentrations and source contributions of 71 volatile organic compounds (VOCs) including C2-C10 nonmethane hydrocarbons, halogenated hydrocarbons, and carbonyls were studied at urban and residential sites in Finland. On the basis of the emission profile and concentration measurements, the contributions of different sources were estimated using a chemical mass balance (CMB) receptor model. It was shown that it is possible to apply CMB in the case of a large number of different compounds with different properties. However, the performance of the model varies significantly for the different compounds. According to the CMB analysis, major sources for these VOCs at the urban site were traffic and distant sources. At the residential site, the contribution due to traffic was minor while distant sources, liquid gasoline, and wood combustion made higher contributions. However, different compound groups or compounds were found to have totally different sources. It was also shown that a biogenic compound, isoprene, also has significant anthropogenic sources and that at some locations wood combustion can be an important source for some VOCs usually considered as traffic-related compounds (e.g., benzene).
Hellén et al. (Fri,) studied this question.