Personal exposure to exhaled contaminants in the near environment of a patient using a personalized exhaust system

Abstract

Exposure to airborne contaminants in hospital environments can lead to infections. In this study, a personalized exhaust system (PES) was placed in the upper part of a hospital bed to efficiently evacuate exhaled contaminants from the environment of a patient. This prevented exhaled particles from freely circulating in the room and being inhaled by an individual in close proximity. Two breathing thermal manikins were used to simulate a contagious patient (P) and a health worker (HW), who was susceptible to inhalation of a fraction of exhaled contaminants. The contaminant exhalation of manikin P was simulated using tiny particles (P0.6) that ranged in size from 0.57 μm to 0.76 μm, and larger particles (P1.1), in the range of 0.94–1.25 μm. A mixing ventilation strategy using two different air changes per hour (ACH), 1.5, and 3, was used in combination with the PES. The reduction in personal exposure to exhaled contaminants was analyzed when only the mixing ventilation strategy was used, or in combination with the PES of the hospital bed. The results showed that in all the investigated cases, the PES contributed to efficiently reducing HW exposure. The exposure (ε) was reduced in the range of 57.2%–80% when manikin P exhaled through the mouth and up to 81.1% when exhalation occurred through the nose. The intake fraction was reduced by more than 30% for the cases where the exhalation of manikin P occurred through the mouth, which was a higher value compared to the case of three ACH.