Abstract：The indoor particle pollution level in two typical commercial environments (shopping mall and commercial office) were observed using a wide-range particle spectrometer (WPS) from 30th Jan. to 7th Feb., 2010. The results showed that particles were mainly distributed in Aitken mode, and the total number concentrations were comparable to those in some developed countries but the mass concentrations were much higher. The diurnal variations of indoor particles indicated the major contribution of outdoor particle sources to indoor particle pollution level. In shopping mall, cleaning and walking could greatly elevate the volume concentration of coarse mode particles to about 4~7 times higher, but had very little influence on the total volume concentration (take 5% of the total). The use of printer could enhance the concentration of particles around 30 nm significantly and last for 20 minutes; in the tobacco smoking event, the elevated concentrations of particles around 100 nm could last for about 6 hours, and the daytime total volume concentration in smoking day was more than twice that in non-smoking day. These results indicated that even though indoor particle level was mainly influenced by outdoor sources, these two indoor sources were also important contributors.
