How I2 disinfects virus in the impinger was studied by using sodium thiosulfate solution

to quench the reactivity of 12 available in the impinger. The same experimental procedure

described previously for sublimation and dissolution of I2 was followed except that the impinger

medium was replaced by a 0. 1M solution of sodium thiosulfate. Thiosulfate anion (S2032-) reacts

stoichiometrically with I2 and reduces it to iodide, which is not virucidal (Berg et al. 1964).

 S Transfer of 12 to Viral Aerosols

 To investigate the inactivation mechanism of direct transfer of 12 to viral aerosols, the

effect of sublimation and dissolution of I2 released from the iodine-treated filter should be

excluded. The use of thiosulfate solution has a limitation in this exclusion because it can react

both with I2 existing free in the impinger solution and with I2 residing on the MS2. Therefore, a

halogen-demanding substance-bovine serum albumin (BSA)-was used, which consumes free

I2 in the impinger solution but competes less aggressively than thiosulfate for 12 on the MS2. The

capacity of BSA to consume all of the I2 released from the filter was predetermined by using the

same experimental configuration for sublimation and dissolution of 12 except that the impinger

contained 0.3%, 3% and 6% BSA and a virus suspension of known concentration. The filtration

experiment was then performed using the selected concentration. Viral aerosols were delivered

as challenges to the iodine-treated filter and collected in both control and experimental impingers

for 1, 5, 10, and 15 mins. The MS2 in the experimental impinger was compared to the

penetrating MS2. For comparison, the same experiment was performed with thiosulfate solution

as the collection medium of the impinger for 15 mins.

Infectivity of Viruses on the Filter

 After 10 hrs of removal efficiency experiments, the test filters were retrieved from the

filter holder in the experimental system and subjected to a vortex mixer (Model M16715,