Ag coated TiO2 anatase nanoparticle suspensions under the normal laboratory room fluorescent lamp killed efficiently Escherichia coli bacteria. When the bacterial suspension contained 105 cells in a volume of 100 μl, the cells were killed in less than 30 min in the presence of 100 ng of TiO2.Malt agar plates were exposed to airborne Penicillium expansum, Aspergillus versicolor, and Eurotium, a Streptomyces and a Bacidomyces species from pure cultures on malt agar plates. Half of the non-inoculated plates contained 15 mg of Ag coated TiO2 nanoparticles. On the next day all the non-inoculated malt agar plates without TiO2 were growing the corresponding microbe while the plates with TiO2 were non-growing. This antimicrobial effect lasted at least 5 days. The results suggest that the moisture-damaged objects after the repair of the original damage could be treated with TiO2 to eliminate the harmful microbes.