Healthcare workers (HCWs) protect themselves against airborne infections with personal protective
equipment (PPE) such as masks, gloves, gowns, etc. in isolation rooms. Additionally, effective
ventilation should mix and dilute the airborne contaminants emitted by any potential sources (e.g. a
patient) and hence provide complementary protection to HCWs. In this study, HCW exposure to patientexhaled
airborne tracers was examined using a full-scale isolation room model with overhead mixing
ventilation. Both the HCW and the patient were simulated with breathing thermal manikins in the
experiments. The performance of the ventilation and the effect of face masks were assessed using smoke
visualizations and tracer gas measurements. The tracer gas experiments showed that: i) closer proximity
to the patient exposed the HCW to higher concentrations of the exhaled tracer; ii) increasing the
ventilation rate only slightly reduced the HCW intake fraction of the patient exhaled tracer close to the
patient; iii) masking the patient with a face mask was more effective than masking the HCW in reducing
the HCW exposure.