Airborne virus survivability during long-term sampling using a non-viable andersen cascade impactor in an environmental chamber

In order to evaluate the survivability of airborne viruses and the sampling performance of an eight-stage non-viable Andersen impactor in typical indoor environments featuring low viral aerosol concentrations, aerosols of a male-specific bacteriophage (MS2), human adenovirus type 1 (HAdV-1), and avian influenza virus (AIV) were sampled size-selectively using the impactor in an environmental chamber. Live virus titer, total virus RNA or DNA concentration, and intensity of a fluorescein tracer were measured to calculate relative virus recovery and virus survival. Viral aerosols were first sampled for 1 and 6 h at 25°C and 50% relative humidity (RH). Virus inactivation and plate overloading were found to be significant in the impactor. Viral aerosols were then sampled at different temperature and humidity levels. MS2 and AIV showed higher survival at lower temperature. Absolute humidity (AH) was found to be a better predictor of virus survival than RH, and the interaction between AH and temperature was not significant. For the tested AH range of 8.8 to 15.2 g/m³, MS2 and HAdV-1 had the highest survival at the lowest AH while AIV had the highest survival at the highest AH. More than 95% of mass collected was for particles smaller than 4.7 m, with the mass median diameter of 1.5 m. In the nebulizer, virus inactivation was not significant at 10 psi (69 kPa) compressed air pressure for up to 6 h of nebulization. Nebulizer analysis also reveals that the use of fluorescein tracer may not always accurately predict the physical loss of virus.