Assessment of airborne bacteria in residential buildings in Benin City, Nigeria

Exposure to bioaerosols poses significant health risks to occupants of buildings, especially in tropical areas due to its climatic characteristics that favour airborne bacterial growth. This study investigated the levels and composition of indoor and outdoor airborne bacteria in residential buildings in Benin Metropolis. Air samples were collected from forty-five randomly selected houses across the five local government areas in Benin City using the passive sampling technique. The culture-dependent 16S rRNA gene technique was utilized in theidentification of the bacterial isolates. The results revealed that the mean concentrations of the indoor and 3 3 outdoor total bacteria varied from 476.1 to 939.3 CFU/m3 and 181.1 to 373.2 CFU/m3 in the wet season, 335.0 3 3 to 457.2 CFU/m3 and 387.2 to 627.8 CFU/m3 in the dry season, respectively. The concentration of indoor and outdoor airborne bacteria varied significantly (P=0.001) during the wet and dry seasons. Basic Local Alignment Search Tool homology showed that the 16S rRNA gene sequences of isolates were related to Proteus mirabilis, Pectobacterium brasiliense, and Enterobacter sichuanensis. The bacterial communities identified are associated with humans and other outdoor environmental media and could lead to critical health outcomes among exposed vulnerable occupants of the buildings. This study, therefore, provides a database for airborne bacteria in residential houses in the study area and could assist in the implementation of effective interventions that reduce the risks and provide a safe environment.