Sensitivity tests of biological safety cabinets' contaminant contention to variations on indoor flow parameters in biosafety level laboratories

Publication date: 1 November 2017
Source:Building and Environment, Volume 124
Author(s): Bruno Perazzo Pedroso Barbosa, Nisio de Carvalho Lobo Brum
Laboratory buildings demand from 4 to 6 times more energy use than conventional applications, and near 50% of this energy use is due to its ventilation system. Previous studies have demonstrated that the strategy of increasing ventilation rates, in mixing ventilation mode, has limited effectiveness on airborne infection control and that the local airflow patterns are more important than a global ventilation rate for that purpose. The primary objective of this research was to assess the sensitivity of contaminant contention to variations on indoor flow parameters, for biosafety level (BSL-Biosafety level) laboratories. Selected testing scenarios were modeled, and the only contaminant source was located inside the biological safety cabinet (BSC-Biological safety cabinets). Numerical modeling, using computational fluid dynamics was performed, in order to assess the sensitivity of BSC's contaminant contention to different values on: generation rate; room thermal load; downflow turbulence; inflow velocity; and room air change rate. Another objective of this research was to assess the time scale related to contaminant transport from the BSC interior to the operator respiration zone, after a concentration build up has taken place inside the BSC. The results showed that BSC's contaminant contention is dependent on room indoor flow pattern, room turbulence level and inflow velocity. The use of higher values of ventilation rates in biosafety level laboratories should be analyzed with caution, because increasing the ventilation rate, with mixed ventilation, decreases the BSC's contaminant contention, due to the enhanced turbulent level, and may increase personnel exposure to hazardous contaminants that leak from the BSC.