For Remnin Hospital:

• Negative results of airborne SARS-CoV-2 RNA concentration may be owed to the negative pressure ventilation and high air exchange rate inside the ICU, CCU, and ward rooms
• The MSAs had low concentrations, this is thought to be sourced from the resuspension of floor dust aerosol containing SARS-CoV-2 transferred from the PAAs

For Fangcang Field Hospital:

• The PARRs have a higher concentration, this may be sourced from the resuspension of the aerosolized virus particles from the surface of medical staff protective equipment while they are removed
• The second batch of TSP samples taken in Fangang MSAs all tested negative following the reduction of patient numbers and implementation of more thorough sanitation measures
• The highest concentration in PAAs was in the mobile toilet room

For PUAs:

• Asymptomatic carriers of COVID-19 may contribute as a source of virus-laden aerosol