Indoor/Outdoor Relationships for Organic and Elemental Carbon in PM2.5 at Residential Homes in Guangzhou, China

J.J. Cao; H. Huang; S.C. Lee; Judith C. Chow; C.W. Zou; K.F. Ho; John G. Watson

doi:10.4209/aaqr.2012.02.0026

Indoor/Outdoor Relationships for Organic and Elemental Carbon in PM2.5 at Residential Homes in Guangzhou, China

J.J. Cao ¹^,2, H. Huang³, S.C. Lee⁴, Judith C. Chow⁵, C.W. Zou³, K.F. Ho⁶, John G. Watson⁵

¹Key Lab of Aerosol, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075, China
²Institute of Global Environmental Change, Xi’an Jiaotong University, Xi’an 710049, China
³School of Environmental Science and Engineering, NanChang University, NanChang 330031, China
⁴Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hong Kong, China
⁵Desert Research Institute, Reno, NV 89512, USA
⁶Chinese University of Hong Kong, Hong Kong, China

Received: February 3, 2012
Revised: June 28, 2012
Accepted: June 28, 2012
Download Citation: ||https://doi.org/10.4209/aaqr.2012.02.0026

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Cite this article:
Cao, J., Huang, H., Lee, S., Chow, J.C., Zou, C., Ho, K. and Watson, J.G. (2012). Indoor/Outdoor Relationships for Organic and Elemental Carbon in PM2.5 at Residential Homes in Guangzhou, China. Aerosol Air Qual. Res. 12: 902-910. https://doi.org/10.4209/aaqr.2012.02.0026

ABSTRACT

Nine residential areas were selected in this study (three homes in urban areas, three homes near roadsides, and three homes in industrial zones) to evaluate the indoor and outdoor relationship and carbonaceous species characteristics of PM_2.5 in Guangzhou, China, during summer and winter 2004. Daily (24 h) average PM_2.5 samples were collected on pre-fired quartz-fiber filters with low-volume samplers and analyzed by the thermal optical reflectance (TOR) method following the Interagency Monitoring of PROtected Visual Environments (IMPROVE) protocol. The average indoor and outdoor concentrations of PM_2.5 were 88.8 μg/m³ and 99.1 μg/m³, respectively. The average indoor OC and EC concentrations were 21.7 μg/m³, and 7.6 μg/m³, respectively, accounting for an average of 25.5% and 8.9% indoor PM_2.5 mass, respectively. The average indoor and outdoor OC/EC ratios were 3.4 and 3.0, respectively. The average I/O ratios of PM_2.5, OC and EC were 0.91, 1.02 and 0.96, respectively. Poor indoor-outdoor correlations were observed for OC in the summer (R² = 0.18) and winter (R² = 0.33), while strong correlations (R² > 0.8) were observed for EC during summer and winter. OC and EC were moderately correlated (R² = 0.4) during summer, while OC and EC correlated well during winter, with a correlation coefficient of 0.64 indoors and 0.75 outdoors. Similar distributions of eight carbon fractions in indoor and outdoor TC pointed to the contributions of motor vehicle exhaust and coal-combustion sources. A simple estimation indicates that about ninety percent of carbonaceous particles in indoor air result from penetration of outdoor pollutants, and indoor sources contribute only ten percent of the indoor carbonaceous particles.