Microbiological contamination of indoor air in university classrooms (Case study: University of Science - Vietnam National University, Ho Chi Minh city)

Abstract

This study was conducted to preliminarily assess microbial contamination of the indoor air inside classrooms at the University of Science - Ho Chi Minh city. At the same time, this study demonstrates the scientific basis of air quality assessment in a school environment and develops long-term direct or indirect solutions to protect the environment and ensure student health. In this project, sampling and quantitative analysis were performed to identify the airborne bacteria and fungi. Samples were collected from classrooms over a period of 4 months (03-06/2019) according to Koch’s sedimentation method. The sampling plates were placed 1 m above the floor and the sampling time was 15 min. The colonies were counted after 24-48 h of incubation at 37±1oC for the bacteria and 70-120 h at 25±1oC for moulds. The results showed bacterial and fungal densities ranging from 359.6-2,427.3 CFU/m3 and 106.1-928.9 CFU/m3, respectively. The bacterial density was 2-3 times higher than the fungal density for all survey sites likely because the origin of these microorganisms is human activity. In addition, the density of bacteria and fungi in the air were also affected by weather and environmental factors. 5 isolated bacteria were identified as Bacillus atrophaerus, Acinetobacter baumannii, Bacillus pumilus, Bacillus subtilis, and Bacillus cereus. The fungi isolates included Aspergillus tamarii, Aspergillus niger, and Fuligo septica. They were all related to human and plant diseases.

Keywords

• airborne microorganisms
• classroom
• indoor air