Experimental measurement of bioaerosol concentrations and containment in long-term care environments

Although many long-term care (LTC) facilities have implemented measures to isolate infectious residents from the general population, most are not designed for airborne infection control, and guidance for retrofitting existing LTC spaces for airborne isolation is limited. The purpose of this study was to evaluate the effect of ventilation, negative pressure, airflow barriers, and other retrofit measures on bioaerosol concentration and movement within long-term care LTC environments. To that end, a series of bioaerosol measurements was performed in an LTC facility under various pressurization and airflow configurations. We arranged active air sampling of DNA-tagged solutions release in the LTC environment, followed by quantitative polymerase chain reaction (qPCR) techniques to measure the released DNA in various spatial locations. Results from aerosol testing in an actual LTC facility suggest that increasing both total and outside ventilation rate had a modest and disproportional effect on the containment of bioaerosols, yet it significantly reduced the time necessary to remove 99% of aerosols from 3 h to approximately 40 min. Significant reductions in aerosol mobility between resident rooms, corridors, and common spaces were also observed with respect to negative room pressurization and anterooms.