To investigate the disinfection efficacy, the number of survived colony on respirators after disinfection treatments was quantified. The E. coli culture was loaded on the respirators applying physical pressure; the bacteria culture penetrated up to the stiffener, and did not penetrate beyond this layer (Figure 5). Without the physical pressure, the loaded culture drop rolled around on the surface of coverweb. The number of loaded E. coli by each layer was correlated with OD470 measurement and expressed as CFU/cm2 substrate surface. Bacteria inactivation or removal efficiency was calculated by: (B0−Bn)B×100 (%), where B0 is the number of live bacteria in the untreated sample area, and Bn is the number of live bacteria in the treated sample area (n = 1~8, each number indicating the eight disinfection methods).