Researcher Studies Air Change Rate and Bioaerosol Transmission

Hospitals are among the most energy intensive buildings in industrialized countries, using more than two-thirds of total energy consumption to maintain climate control and indoor air quality (IAQ). Yet hospital-acquired infections (HAIs) afflict approximately 8 percent of the inpatient population and claim more than 115,000 lives each year in Europe and the U.S. alone. Grosskopf (2013) conducted a series of four tests in a hospital to observe removal rates and containment of synthetic bioaerosols with respect to air change rate, air pressure differential and door position in a general patient room, and, an isolation patient room.

Air change rates were not found to be effective in proportionately reducing aerosol concentrations within patient rooms when the aerosol was continuously released. Specifically, increasing mechanical ventilation rates from 2.5 to 5.5 air changes per hour (ACH) reduced aerosol concentrations only 30% on average. An air pressure differential of 2.5Pa, however, was found to be effective in containing aerosol transport from patient rooms to adjacent corridors except in cases where isolation anterooms were negatively pressurized with respect to isolation spaces. Door position and door motion was also found to have a significant effect on aerosol containment.

Reference: Grosskopf K. Poster presentation P396 at the 2nd International Conference on Prevention and Infection Control (ICPIC 2013): Balancing ventilation and energy use in hospitals: a case study of bioaerosol transport in healthcare environments. Antimicrobial Resistance and Infection Control 2013, 2(Suppl 1):P396.