Indoor/outdoor relationships of organic carbon (OC) and elemental carbon (EC) in PM2.5in roadside environment of Hong Kong

K. F. Ho, J. J. Cao, Roy M. Harrison, Shuncheng Lee, K. K. Bau

Research output: Journal article publicationJournal articleAcademic researchpeer-review

93 Citations (Scopus)


Five buildings located near roadsides (an office and a classroom with mechanical ventilation (MV) and three residences with natural ventilation (NV)) were selected with a view to characterising indoor and outdoor concentrations of organic (OC) and elemental carbon (EC). PM2.5samples were analysed using a thermal optical reflectance (TOR) method for OC and EC concentrations. The average 24-h PM2.5outdoor concentration was 78.4 μg m-3, whilst the average outdoor OC and EC concentrations were 12.6 and 6.4 μg m-3, respectively, accounting for 17% and 9%, respectively of the outdoor PM2.5mass. The average 24-h PM2.5indoor concentration was 55.4 μg m-3of which indoor OC and EC were 11.3 and 4.8 μg m-3, respectively, accounted for 22% and 9%, respectively. The mean value of indoor to outdoor ratios (I/O ratios) of PM2.5was 0.80, with a close correlation between indoor and outdoor PM2.5concentrations, especially in the NV residences. The average I/O ratios of OC and EC were 1.02 and 0.80, respectively. The higher ratio for OC reflects indoor sources of OC, which do not appear to occur for EC. The major source of indoor EC, OC and PM2.5, however, appears to be penetration of outdoor air, with a much greater attenuation in the MV buildings studied.
Original languageEnglish
Pages (from-to)6327-6335
Number of pages9
JournalAtmospheric Environment
Issue number37
Publication statusPublished - 1 Dec 2004


  • Elemental carbon
  • Indoor air
  • Organic carbon
  • PM 2.5
  • Roadside

ASJC Scopus subject areas

  • General Environmental Science
  • Atmospheric Science


Dive into the research topics of 'Indoor/outdoor relationships of organic carbon (OC) and elemental carbon (EC) in PM2.5in roadside environment of Hong Kong'. Together they form a unique fingerprint.

Cite this