Research Conducted by Associate Professor, Kevin Grosskopf
Secondary Exposure Risks to Patients in Airborne Isolation
Improvements in ventilation techniques and isolation procedures have been widely credited with the decline in nosocomial transmission of tuberculosis and other airborne diseases beginning in 1993. By comparison, little effort has been made to study the risk of isolation patients acquiring secondary infections from contaminated air migrating into negatively pressurized isolation rooms from adjacent spaces. As a result, an actual hospital was used to observe the transport of synthetic aerosol from a nursing station and general patient room to a nearby airborne infectious isolation room (AIIR). Aerosols ≤3.0µm (viruses and most bacteria) were found to be capable of migrating 14.5m (47.6ft) from a general patient room to an AIIR anteroom entrance in <14 minutes at concentrations 2-5 times greater than ambient (e.g. background). Concentrations of aerosols ≤3.0µm within the anteroom and isolation room, however, remained virtually unchanged from ambient levels, indicating the effectiveness of door position and (or) ventilation. In contrast, higher deposition rates appeared to limit the migration of aerosols < 3.0µm to the entrance of the general patient room (4.5m).