Quality criteria

The Centers for Disease Control and Prevention (CDC) recommends that, if used for surface sterilization, ensure the energy output is sufficient to kill microorganisms. The lamp should be tested and the intensity should not be less that 40 micro watts per square centimetre (µW/cm2) at the center of the work area. The light intensity can be measured using a photometer.

1. Determining fit factor of mask
Use a commercial fit test system (TSI PortaCount Plus Respirator Fit Tester and N95- Companion Module model 8095) to measure respirator fit by comparing the concentration of microscopic particles outside the respirator with the concentration of particles that have leaked into the respirator. A Wilcoxon sign rank test is then conducted to show that there is a significant difference between wearing a mask and not wearing a mask.

2. Determining the effect of masks in preventing dispersal of droplets & aerosol
Construct enclosed 0.5-m3 mobile sampling chamber and place it in a 22.5-m high-frequency particulate air-filtered environmental room. Place 4 settle plates in the chamber to sample for droplets, together with a 6-stage Andersen sampler to sample and separate small particles. Attach a Casella slit-air sampler to the chamber. Add Tryptose soya agar as culture medium. Let volunteers wearing the mask cough twice into the box, and sample the air inside for 5 minutes. High-frequency particulate air filter the air within the chamber for 5 minutes between each sample to prevent cross-contamination between samples. Incubate plates for 48 hours at 37°C before counting the median colony forming units. If there are lesser colony forming units formed while wearing the mask when compared to not wearing a mask, the mask can be shown to be effective.

(Obtained from here - click for more information)