Determination of the indoor air bacterial load and associated factors in primary schools in Hawassa City, Ethiopia, 2023. A comparative -cross-sectional study.

Abstract

Background: Indoor environments, particularly in schools, are a significant source of bacterial exposure, posing a public health risk. The aim of this study was to investigate the bacterial load and associated factors in the indoor environments of governmental and private primary schools in Hawassa, City, Ethiopia, 2023.

Methods: A comparative cross-sectional study design was used in March, 2023; in 56 randomly selected classrooms focusing in five governmental and five private primary schools in Hawassa, City. The bacterial load was estimated using the settle-plate method of passive air sampling. Differences in the mean bacterial load between government and private primary schools were evaluated using a non-parametric test. Multiple linear regression analysis using log-transformed data was performed.

Result: The average bacterial load in government primary schools was 8684.84 CFU/m3; while in private schools, it was 4396.43 CFU/m3. The isolated bacterial species included coagulase-negative Staphylococcus species (CoNS), gram-negative Bacillus species, gram-positive Bacillus species, and Staphylococcus aureus. A significant difference in the mean bacterial load (p=0.002) was observed between government and private primary schools with private primary schools showing lower levels. In government schools, the bacterial load was significantly associated with classroom cleanliness, occupant density, cleaning frequency, and classroom area. Conversely, the bacterial load in private schools showed strong association with the occupant density, cleaning frequency, relative humidity, and ventilation conditions.

Conclusion: In government and private primary schools, the level of bacterial loads exceeded the WHO -criteria. This study revealed significant differences in indoor bacterial loads between government and private primary schools, with private schools showing lower levels. The correlation between bacterial load and environmental factors was distinct in each setting. As a recommendation; improving cleanliness, layout optimization, ventilation improvement, and hygiene education for both sectors, with regular air quality monitoring are crucial for tracking progress.