“…TiO 2 PCO has been applied for the purification of volatile organic compounds (VOCs) (Luo & Ollis, 1996;Yu & Lee, 2007; and for the disinfection of microbial contaminations in liquid phase (Cho, Chung, Choi, & Yoon, 2005;Christensen, Curtis, Egerton, Kosa, & Tinlin, 2003;Lee, Nishida, Otaki, & Ohgaki, 1997;Sunada, Kikuchi, Hashimoto, & Fujishima, 1998). Moreover, the mechanisms of PCO for the removal of microbial contaminations and VOCs have also been reported (Cho et al, 2005;Maness et al, 1999;Sunada et al, 1998;Yu & Lee, 2007;. Lin and Li (2003a) demonstrated that the effectiveness of a photocatalytic filter on the removal of bioaerosols was insignificant, which might be caused by a lack of enough time (on the order of 1 s) for the microorganisms to contact and react with the TiO 2 and reactive species generated by the PCO reaction.…”