Abstract：To investigate the relationship between indoor and outdoor VOCs, the air in and out of an idle room were simultaneously sampled from Nov.5 to Dec.11, 2014. 98 kinds of VOCs were quantitated and discussed by dividing them into five categories according to their functional groups, and they are alkanes, olefin, aromatics, halogen and oxygenated hydrocarbons, respectively. In this paper, we disicussed the concentration levels, I/O, indoor and outdoor relevance as well as the correlation between different categories of VOCs. At last, we roughly estimated the contribution of outdoor VOCs sources on indoor VOCs concentration. Results showed that indoor VOCs had higher concentritions than outdoor, and alkanes>oxygenated hydrocarbons>halogen hydrocarbons>olefin. Five categories both had indoor and outdoor sources of VOCs. For the indoor and outdoor relevance of VOCs, olefins were related to the worst while oxygenated hydrocarbons the best. Meanwhile there came to the conclusion that halogen hydrocarbons > alkanes> aromatics. Alkanes-Olefin shared the best correlation both in the indoor and outdoor samples (rin=0.805, rout=0.888, P￡0.01), while halogenated hydrocarbons-oxygenated hydrocarbons shared the worst correlation (rin=0.491, P￡0.05; rout= 0.529, P￡0.01). Outdoor source contribution rate changed between five kinds of VOCs. Halogenated hydrocarbon contributed the most (56.57%), followed by alkanes (46.64%), olefins (40.10%), oxygenated hydrocarbons (33.98%) and aromatics (20.67%). In addition, the concentration levels of VOCs, I/O, indoor and outdoor correlation and the correlation between substances after APEC summit were higher than the corresponding value before the summit.
