Assessment of indoor and outdoor microbial air quality of cafeterias of an educational institute

This study investigated airborne microbial levels of two indoor locations and one outdoor location of three cafeterias (A, B and C) of a university campus. Sampling locations of cafeteria A and B included closed and semi closed spaces (both naturally ventilated) while for the case of cafeteria C (facilitated with centralized HVAC), both locations were closed. Microbial air samples were collected during the peak operating hours in duplicate during months of April and May 2017. Results showed higher fungal levels as compared to bacterial concentrations for most of the sampling locations. Highest bacterial count was observed in the closed area of cafeteria B (mean: 214.7 CFU/m(3)) and lowest in cafeteria C (mean: 70.5 CFU/m(3)). Moreover, highest fungal count was found in semi-closed space of cafeteria A (mean: 525.6 CFU/m(3)) and lowest in cafeteria C (mean: 44.9 CFU/m(3)). Bacterial concentration levels were found to be mainly linked with indoor sources while fungal levels were associated with outdoor sources. Fungal genera sampled on the monitored sites were identified as Cladosporium spp. (46%), Geotrichium spp. (8.6%), Ulocladium spp. (8.5%), Alterneria spp. (7.9%), Fuserium spp. (6.6%), Curvularia spp. (3%), Aspergillus spp. (2.4%) and Penicillium spp. (1.3%). Whereas gram positive cocci (90%) were found to be most abundantly prevailing class of bacteria. The most dominant bacterial genera found were Staphylococcus spp., Kocuria spp., Bacillus spp. and Micrococcus spp.