Microbial Assessment of Indoor Air Quality of Laboratory Sections in Obong University, Obong Ntak, Nigeria

Background: Poor indoor air quality constitutes a significant health problem in schools, mostly in the laboratory sections due to a high number of students per laboratory vis-a-vis space confinement, insufficient outside air supply, poor construction and maintenance of laboratory buildings. Aim: This study was carried out to assess the air quality and identify airborne bacteria and fungi in selected sections of Obong University Laboratory. Materials and Methods: Institutional based study employing passive air sampling, settle plate or gravitational sampling method to collect airborne bacteria and fungi was conducted in 3 selected laboratory sections of the University. Culture, isolation, colony count/air quality assessment and identification of airborne bacteria and fungi were done using standard methods. Results: The mean bacterial load was 111.75 CFU/m3 in the morning and 125.25 CFU/m3 in the afternoon. The highest and lowest bacterial loads were recorded at the Laboratory Animal Room (LAR) to be 165 CFU/m3 and 201 CFU/m3 in the morning and afternoon, respectively. The total fungal load was 100 CFU/m3 in the morning and 170 CFU/m3 in the afternoon with the mean estimate of 25 CFU/m3 in the morning and 42.5 CFU/m3 in the afternoon. The highest fungal load was equally estimated in the LAR at a percentage rate of 55% and 54.12% in the morning and afternoon, respectively. The results of the indoor air quality assessment of the different laboratory sections revealed a very low (<50 CFU/m3) to low (50-100 CFU/m3) degree of both fungal and bacterial air pollution within the sampling time. A total of 3 bacterial and 5 fungal species were isolated as follows: Staphylococcus aureus 16(61.5%), coagulase negative Staphylococcus species (CoNS) 7 (27%) and Bacillus species 3 (11.5%); Aspergillus flavus 7 (25%), Aspergillus niger 8 (28.5%), Penicillium chrysogenum 4 (14.3%), Rhizopus spp. 5 (17.9%) and Fusarium spp. 4 (14.3%). The levels of indoor airborne bacteria and fungi as revealed in this study were found to be within the acceptable and permissible limits of microbial load ≤500 CFU/m3. Conclusion: Attention should be given to control those human, animal and environmental factors which favour the proliferation of bacteria and fungi in the indoor environment of school laboratories to safeguard the health of students, lecturers and laboratory personnel in the University. Keywords: Microbial Quality, Indoor Air, Laboratory, Colony, Pollution