Characterization of the indoor near-field and far-field aerosol transmission in a model commercial office building

Abstract

To simulate the exposure potential of infectious aerosol such as SARS-CoV-2 in an office building setting, experimental studies for airborne particle transmission have been conducted in a model commercial office building at the Oak Ridge National Laboratory. The synthetic test aerosol particles had diameters similar to that of viral particles, in the nanometer size range of genetic fragments. Thus, the test aerosol provided a realistic representation of SARS-CoV-2 viral particle transmission. The study results, which are still being analyzed carefully at the present, suggest that in a door-closed single room setting, the heating, ventilating, and air-conditioning (HVAC) system can facilitate aerosol transmission, and 10 measuring points in a single room report the normalized concentration ranged from 0.45 to 0.66. Additionally, at a measuring point 6 feet away from the source, the aerosol concentration can reach a plateau normalized concentration of about 0.6 within 30 minutes. When interior doors were closed, aerosol particle transmission into adjacent rooms occurred through the building HVAC system, at a lower rate compared to the open-door scenario. If the interior doors were open, however, then the transmission into adjacent rooms depends on building indoor air movement and distance from the source. The building HVAC system provided an approximately less than 10% aerosol transmission rate, while transmission through a door opening can add up to 40% of transmission into adjacent rooms from the source location.