One important thing considered in the use of the biocidal filter is the health effect of the

incorporated antimicrobial agent. Since iodine vapor irritates mucous membranes and adversely

affects the upper and lower respiratory system, its inhalation can cause coughing and tightness in

the chest (Cameron 2002). The iodine concentration in the air passing through the iodine-treated

filter is as low as the detection limit of the analytical method, which is 0.004 mg/m3 (OSHA

1994). It is much less than the 8-hr Time Weighted Average-Threshold Limit Value (TWA-

TLV) of 1 mg/m3, which is the level below which a worker is expected to have no adverse health

effect resulting from chronic exposure (OSHA 2000).

 In conclusion, both the iodine-treated and untreated filter media present effective

approaches to the removal of bacterial spore aerosols. They achieve high viable removal

efficiency without increasing pressure drop by incorporating iodine as a disinfectant into the

filter medium. Furthermore, the deactivation of the collected bacterial spore aerosols is

enhanced by the iodine-treated filter compared to the untreated filter before the filter medium

loses significant amount of iodine due to sublimation and dissolution.