Carbon profile of residential indoor PM1 and PM2.5 in the subtropical region

Carbon profiles of PM1 and PM2.5 were measured simultaneously in the indoor and outdoor air of 10 homes in the Taipei urban area in both summer and winter seasons. It was indicated that the average indoor and outdoor concentrations were found to be 25.88 and 25.86 μg m−3 for PM1, as well as 37.60 and 37.26 μg m−3 for PM2.5, respectively. In addition, the average summer and winter levels were found to be 25.13 and 26.70 μg m−3 for PM1, as well as 36.45 and 38.51 μg m−3 for PM2.5, respectively. There were no significant concentration differences observed in indoor/outdoor (I/O) and summer/winter PM1/PM2.5 levels. Moreover, the median value of I/O ratios of PM1 and PM2.5 was observed to be 1.0 which might demonstrate that there was no presence of significant indoor PM sources in this subtropical region. In addition, it was found that PM1/PM2.5 mass ratios were 0.68. Regarding carbon profiles, it was observed that mass fractions of total carbon in PM1 and PM2.5 were 0.50 and 0.46. It was demonstrated that indoor/ambient combustion-related fine particle play an important role in urban residential environments.