College of Public Health Grand Rounds
Wednesday, October 30, 2013
“Ventilation and the Transport of Bioaerosols in Healthcare Environments.” Presented by K.R. Grosskopf, PhD, Associate Professor of Engineering, University of Nebraska-Lincoln and Terry Stentz, Ph.D., MPH, CPE, CPC, Associate Professor of Engineering, University of Nebraska-Lincoln
Hospitals are among the most energy intensive buildings in the U.S., using more than two-thirds of total energy consumption to maintain climate control and indoor air quality (IAQ). In spite of this, hospital acquired infections (HAIs) claim more than 90,000 lives and cost more than $US 20 billion each year. As a result, a series of tests were conducted in an actual hospital to observe containment and removal of synthetic respiratory aerosols (0.3-10.0µm) with respect to directional airflow and ventilation rate within a general patient room, an airborne infectious isolation room (AIIR) and corridor. Ventilation rates were not found to be effective in proportionately reducing aerosol concentrations within patient rooms. Specifically, increasing outdoor air (OA) ventilation from 2.5 to 5.5 air changes per hour (ACH) reduced aerosol concentrations only 25-30% on average. Directional airflow (≥2.5Pa), however, was found to be effective in containing aerosol transport from patient rooms to adjacent corridors. Within corridors, aerosols ≤3.0µm were found capable of migrating distances exceeding 31m (100ft). Door position, door motion and personnel movement were also found to have a significant effect on air pressure relationships and subsequent aerosol containment. The results of this case study, when compared to other similar studies, may identify optimal levels of ventilation that maximize airborne infection control while minimizing energy use.