The stability and elimination of mammalian enveloped and non-enveloped respiratory viruses in indoor air: Testing using a room-sized aerobiology chamber.

We assessed the viability of aerosolized human betacoronavirus OC43 (HCoV-OC43; ATCC VR-1558), human rhinovirus-14 (RV-14; ATCC VR-284) and feline calicivirus (FCV; ATCC VR-782) as representative enveloped and non-enveloped respiratory viruses of mammals in indoor air under ambient conditions (relative humidity 50±10% and air temperature 22±2°C) using a room-sized (25 m3; 900 ft3) aerobiology chamber. All virus suspensions contained a soil load to simulate the presence of body fluids and they were separately aerosolized into the chamber using a six-jet Collison nebulizer. A muffin fan was used to uniformly mix the air inside the chamber and to keep the aerosols airborne. A slit sampler with Petri plates containing 3% (wt./vol) gelatin was used to collect the air samples. The gelatin was liquefied in an incubator and assayed for infectious virus as plaque-forming units (PFU). The rates of biological decay of HCoV-OC43, RV-14 and FCV were 0.0052±0.00026, 0.0034±0.0027 and 0.0081±0.0031 (as log10 PFU/m3/min), respectively. We also assessed a HEPA filter-based stand-alone air purifier against the experimentally aerosolized viruses and the device could demonstrate >3-log10 reductions in the viability of the three viruses in 46, 62 and 41minutes, respectively. Therefore, we can now investigate the stability of mammalian viruses in indoor air as well as air decontamination technologies against them under field-relevant conditions.