Temporal and spatial aerosol transmission from the exhalation of an infected person in an office environment

¹ Aalto University, School of Engineering, Department of Mechanical Engineering, Sähkömiehentie 4, 02150 Espoo, Finland
² University of Eastern Finland, Department of Environmental and Biological Sciences, Yliopistonranta 1 E, 70211 Kuopio, Finland
³ Nanjing Tech University, College of Urban Construction, Department of HVAC, 211899 Nanjing, China

^* Corresponding author: sami.lestinen@aalto.fi

Abstract

The paper reports office test chamber experiments with an exposed breathing thermal manikin (6 L/min) and an infected exhalation simulator (6 L/min) connected with a thermal dummy. The motivation was to investigate effects of different protection methods at workstation when an infected person is working in the room. The protection methods were room air purifier, personal air purifier, FFP2-mask, and workstation partition panels. The objective was to measure temporal and spatial concentration characteristics at the exposed breathing zone. The exhale of infected model was aerosolized by using a Blaustein atomizer (BLAM), syringe pump and paraffin oil (0.6 mL/h). The concentrations were measured with TSI optical particle sizers. The ventilation method was mixing ventilation from a perforated duct. The indoor air change was 1.7 1/h (ACH). The experimental set-up was carried out at 6 workstations around the infected person. The temporal and spatial evolution was measured from zero concentration to steady concentration level. The results indicate that the room air purifier and the facemask can efficiently reduce exposure whereas the personal air purifier had a moderate reduction. The partition panels had only a minor effect on exposure. The lowest exposure was found when the individuals were sitting at the same side far from each other.