Factors influencing the results of air samplers in closed, air-conditioned patient rooms—a numerical study

Several air sampling studies have been conducted to assess the risk of airborne transmission since the outbreak of SARS-CoV-2 in late 2019. However, differences in sampler positioning and positive collection results in more distant locations suggest an interaction between the sampler and the indoor air flow, altering the aerosol distribution. This study aims to investigate this influence by studying multiple collector positions, patient exhalation modes, and two ventilation setups in a 3D simulation model using implicit large-eddy simulations along with evaporative Lagrangian particles. The results of this study show a higher total aerosol particle amount in the patient room with the deployment of a sampling device, possibly increasing infection risk for medical personal during and shortly after a sampling procedure. Furthermore, the variation of the collector position reveals an impact on the sampling yield, thus rendering even more distant positions viable and potentially beneficial in terms of maintaining sampler performance and increasing patient comfort. Moreover, the influence of ventilation was investigated suggesting the deactivation to increase aerosol concentration during sampling campaigns for efficient sampling. Additionally, results indicate an impact on room flow by air samplers and subsequent sampling yield, potentially necessitating reassessments of conclusions drawn from previous sampler studies. Finally, it can be concluded that future air sampling campaigns, which are preliminarily assessed using numerical simulation, could benefit from advantageous positioning to aid sampling success. © The Author(s) 2025.