The aerodynamic behavior of respiratory aerosols within a general patient room

Abstract

Hospital-acquired infections claim on average 90,000 lives each year in the United States, nearly 3 times the number of annual highway deaths. Although fewer than 15% of hospital-acquired infections are directly attributable to airborne transmission, more than one-third may be caused by surface microbes aerosolized by the movement of air from building systems, people, and equipment. In response, an actual hospital was used to map the spatial dispersion of synthetic respiratory aerosols with respect to particle size, airflow, door position, and healthcare worker movement between a general patient room and corridor. Respirable aerosols 0.5 μm to <1.0 μm were found to exhibit distinctly different aerodynamic behaviors when compared to aerosols 1.0 μm–10.0 μm. Specifically, aerosols <1.0 μm appeared to disperse randomly and uniformly throughout the test space with significantly less regard to mechanical airflow, pressure relationships, door position, and personnel movement when compared to aerosols 1.0 μm–10.0 μm. Since expiratory droplets <1.0 μm are believed to be capable of both carrying virus and penetrating into the alveolar region of the lung, these particles may present unique challenges for ventilation systems designed to protect the healthcare population from airborne viral transmission.