Characteristics of Residential Indoor Carbonaceous Aerosols: A Case Study in Guangzhou, Pearl River Delta Region

Nine residences located in Guangzhou were selected to characterise indoor fine particles (PM2.5), organic carbon (OC) and elemental carbon (EC) during summer time. These nine residences were classified into 5 types, urban without smoker, urban with smoker, newly remodelled urban, roadside and suburban. The average indoor PM2.5 concentration was 47.4 mu g/m(3), consisting of 12.5 mu g/m(3) of OC and 4.4 mu g/m(3) of EC. OC and EC accounted for 24.6 % and 9.9 %, respectively, of the indoor PM2.5 mass. Higher PM2.5, OC and EC concentrations were observed in the urban residences with smokers and the roadside residence, suggesting the importance of indoor sources and outdoor penetration. The highest PM2.5 and OC concentrations were observed in one of the urban residences with a smoker due to the contribution of indoor sources and the poor condition of ventilation in the kitchen. The highest EC was observed in the roadside residence, indicating the penetration of outdoor traffic emissions. Urban residences without smokers and recently remodelled residences had similar PM2.5, OC and EC concentrations. The suburban residence had the lowest PM2.5 and OC concentrations, while the EC concentration was lower than roadside residence but similar to other urban residences. Eight carbonaceous fractions by thermal/optical reflectance (TOR) method, namely OC1, OC2, OC3, OC4, OP, EC1, EC2 and EC3, were also studied. OC2, OC3 and EC1 were the most abundant fractions. EC1 was found to be the carbonaceous fraction which was mainly from outdoor vehicular emissions. OC2 and OC3 were likely to be contributed by smoking and cooking emissions in indoor microenvironments.