Assessment of Microbial Load in Indoor Air of Selected Primary Schools in Maiduguri, Borno State

Indoor air quality in school environments directly influences the health and academic performance of children, yet airborne microbial contamination in Nigerian primary schools remains inadequately characterised. This study assesses the microbial load in indoor air of ten selected primary schools in Maiduguri, Borno State, North East Nigeria, comparing classrooms, staffrooms, and toilet facilities. Air samples were collected using the passive settle plate method, exposing blood agar and Sabouraud dextrose agar plates at standardised heights for one hour per session, with sampling conducted during school hours and after-school periods. Total bacterial count, total fungal count, and identity of dominant isolates were determined. Bacterial counts in classrooms ranged from 102 to 1,840 colony-forming units per cubic metre, exceeding the WHO guideline of 500 cfu/m3 in 60 percent of classrooms sampled during school hours. Staphylococcus aureus, Streptococcus species, and Bacillus species were the most frequently isolated bacteria. Aspergillus species dominated the fungal flora. Toilet facilities showed the highest combined microbial loads. Overcrowding, poor ventilation, and inadequate cleaning schedules were identified as primary contributors. A significant positive correlation was observed between classroom occupancy and bacterial count. The study recommends improved ventilation design in school construction, regular cleaning protocols, and microbial air quality standards for Nigerian primary schools. Keywords: indoor air quality, airborne bacteria, primary school, Maiduguri, microbial load