Experimental study of ventilation performance of three ventilation strategies using aerosols and tracer gas

• The clean air flow rate varies according to the position at which it is measured. • A mixed ventilation system is more efficient with CO 2 than with particles. • Particle efficacy in worker inhaled volume increased with personal exhaust system. • Personal exhaust system had not effect on intake fraction of healthcare worker using CO 2 . Effective ventilation plays a crucial role in reducing the risk of infection by airborne contaminants. This study was conducted in a hospital ward of specific dimensions (41.58 m 3 ) equipped with two respiratory thermal manikins: a healthcare worker and an infected patient. Three ventilation strategies were employed in the ventilation system: supply and exhaust air through upper grilles, upper and lower grilles, and swirl diffusers with lower grilles. The air flow rate of the ventilation system was maintained constant at 200 m 3 /h. The airflow was distributed 50-50% by a combination of a personalised ventilation system and personalised exhaust system. The effectiveness of a ventilation system and its combination with a personalised exhaust system was investigated using aerosol and tracer gas techniques. The efficacy of contaminant removal was evaluated in both the patient and healthcare inhaled volume. Determination of the clean air flow rate of the three ventilation system strategies at inhaled volume was carried out. Also, the exposure of healthcare worker to the contaminants exhaled by infected patient in the microenvironment formed by both was analysed. Experimental findings revealed that CO 2 showed a higher ventilation efficiency compared to particles, independently of the ventilation strategy used. The highest clean air flow rate values were detected in the inhaled volume of patient infected. On the other hand, the highest particle removal efficiency was observed in swirl diffusers with lower grilles, which combined the ventilation system with the PES. This strategy also showed the lowest exposure values in the microenvironment.