Removal of bioaerosols at varied humidities by glasswool filter

This study presents the creation and evaluation of a high-strength, wet aerosol signal containing surrogate viruses and bacteria into a system capable of detecting several logs of removal by filtration. The system consisted of a collision six jet nebulizer, a copper pipe pre-mixing chamber (1" diameter and 32.7" length), a plexi-glass stabilization chamber (3.4" diameter and 9.6" length), and a collection system comprised of a glass impinger with Teflon filter. The partial pressure for the nebulizer was 10 psi, and the total flow rate through the system was 6 L/min. The system was evaluated multiple times using a cocktail signal of E. coli bacteria, MS2 coliphage (27 mn) and PRD1 bacteriophage (62 nm). The dosed viable counts of the surrogates in the nebulizer were around 10 9 colonies/mL for E. coli, and 109 pfu/mL for MS2 and PRD1. A strong signal was reliably recovered from the collection system (106 colonies/L air and 106∼107 pfu/L air for bacteria and bacteriophage, respectively) during 5-minute sampling. The system was capable of generating stable and reproducible bioaerosol signals.;The removal efficiency for E. coli and MS2 using the glasswool filter was at least 5-log removal at indoor humidity (20%-50%) and room temperature (20°C). The Relative Humidity (RH) did not affect the removal efficiency of E. coli at the beginning of filtration, but over time. RH affected the removal efficiency of MS2 at the earlier stage of filtration, which the removal efficiency was greater at 50% RH than 23% RH. MS2 also did not associate with E. coli in the aerosols to a great extent since they have different, distinctive breakthrough pattern.;This study found that generated bioaerosol signal was captured and recovered without significant loss by immediate extraction. It was also found that shaking deactivated approximately 34% PRD1, and drying at room humidity and temperature for only one hour deactivated approximately 2 logs PRD1 captured on glasswool filters. Shaking did not affect the viability of MS2 and there was less than one-log deactivation even after more than 24-hour drying at room temperature for MS2. Therefore, MS2 was a better viral surrogate for wet bioaerosol study than PRD1.