Characteristic of residential indoor carbonaceous aerosols in Guangzhou, Pearl River Delta Region

Nine residential areas, located in Guangzhou, were selected to characterize the indoor concentrations Of PM2.5, organic carbon (OC) and elemental carbon (EC) from June to July, 2003. PM2.5 samples were analyzed by using a thermal optical reflectance (TOR) method following the Interagency Monitoring of PROtected Visual Environments (IMPROVE) protocol for OC and EC concentrations. The average 24-h PM2.5 indoor concentration was 47.4 mu g m(-3), whilst the average indoor OC and EC concentrations were 12.5 mu g m(-3) and 4.4 mu g m(-3) respectively, accounting for 24.6% and 9.9% respectively of the indoor PM2.5 mass. The average OC/EC ratio of indoor PM2.5 is 3.3 and ranged from 1.2 to 21.2 for indoor residential environments while the average OC/EC ratio of outdoor PM2.5 is 2.3 and ranged from 0.9 to 5.6. Good correlation (R=0.95) was observed between the indoor PM2.5 and TC for overall microenvironments indicating that TC was the dominant component of PM2.5. However, the correlation coefficient between the indoor OC and EC was 0.70 due to the influence of the indoor emissions.