Controlling microbial activity on walls by a photocatalytic nanocomposite paint: A field study

Bacteria and fungi that grow on the walls can cause allergic reactions and infectious diseases in human. We proposed a low-cost and easy-to-operate testing protocol for large scale field studies to evaluate the long-term antimicrobial performance of a novel WO_x paint in 2 primary schools.

In Tun Mun and Tin Shui Wai schools, WO_x paints were painted on semi-outdoor and indoor walls and daily chlorine disinfection was applied after class in TSW School. A guidance was proposed for the protocol using the ATP biofluorescence method for large-scale field studies. ATP swab samples were taken at locations with and without the WO_x paint on a control basis with a sampling frequency once a week for three months. The ATP values were then processed and presented in box plots.

In both schools, the median log-scale ATP values of walls with WOx paint were at least 0.5-log lower than those without WOx paint. The WO_x paint also performed better than daily chlorine disinfection in reducing microbial activities in long-term.

The proposed testing protocol is suitable to evaluate long-term performance of an antimicrobial paint by analyzing its microbial activity in large-scale field tests. The WO_x paint shows long-term effectiveness in reducing microbial activities on wall surfaces in both indoor and semi-outdoor environments.