The suitability of a glovebox and of a covered still air box design for semi-sterile applications in environmental monitoring

Laminar flow cabinets (LFCs) ensure a safe working space within which product manipulation can be carried out safely excluding contaminations of the product with the environmental microorganisms. However, for environmental monitoring applications mobile laboratories are required and these prefer the lighter gloveboxes (GB; restricted arm movement) or still air boxes (SAB; free arm movement) over the heavier, more expensive LFCs, which need to be regularly maintained. Nevertheless, the efficiency of simple GBs/SABs (no HEPA filter), in providing semi-sterile working conditions has yet to be clearly defined. Consequently, our aim was to assess the suitability of GBs/SABs for semi-sterile applications by using passive and active bioaerosol sample collection procedures within the interior spaces of these boxes. Prior to sample collection the boxes were pre-treated with different spraying preparations (70% ethanol, two percent detergent or sterile water). For a greater restriction of bioaerosol entry, SABs were constructed with covered arm ports and these were classified as partially covered (SAB_PC) and completely covered SABs (SAB_CC). Results showed that ethanol sprayed GB and SAB_CC exhibited microbial aerosol colony counts of zero after one hour of passive sample collection, and active sample collection revealed counts ranging between 1.9 (for GB) - 2.3 Log₁₀CFU/m³ (for SAB_CC). However, ethanol sprayed SAB and SAB_PC were ineffective having colony counts of 6.9 and 6.5 Log₁₀CFU/m³, respectively. Other spraying regimes resulted in even higher colony counts (up to 7.3 Log₁₀CFU/m³). Therefore, the ethanol sprayed GB and SAB_CC could effectively be used for semi-sterile applications, with the SAB_CC allowing for an unrestricted arm movement within it.