Airborne microbial contamination in classrooms and office of the biological cciences building, Faculty of Science, Ubon Ratchathani University

Abstract

This study aimed to evaluate the airborne concentrations of bacteria and fungi, examine their relationship with physical factors (temperature, relative humidity, and wind speed), and compare microbial counts between morning and afternoon sessions. The research was conducted across five classrooms and one office room in the Biological Sciences Building, Faculty of Science, Ubon Ratchathani University. Air samples were collected using a Single-Stage Impactor in accordance with the standard NIOSH Method 0800 from June to July 2025, yielding a total of 96 samples taken at a height of 1.5 meters from the floor. The results were evaluated against the recommended guidelines of the Department of Health (Thailand), SPRING Singapore, and NIOSH. Data were analyzed using Paired Samples Test and Spearman Rank Correlation at a 95% confidence level (p < 0.05). The results indicated that bacterial concentrations ranged from 75.58 to 226.74 CFU/m³ in the morning and from 72.64 to 388.69 CFU/m³ in the afternoon. Fungal concentrations ranged from 211.99 to 400.47 CFU/m³ in the morning and from 106.99 to 314.09 CFU/m³ in the afternoon. The total microbial counts detected in all rooms complied with the recommended standards of the Department of Health and SPRING Singapore (500 CFU/m³), as well as NIOSH (1,000 CFU/m³). Correlation analysis revealed that temperature, relative humidity, and wind speed had no statistically significant correlation with airborne bacterial or fungal levels. Furthermore, no statistically significant differences were observed between morning and afternoon microbial levels for either bacteria (p = 0.201) or fungi (p = 0.109). Recommendations from this study suggest that, regular cleaning of furniture, desks, chairs, and shelves is recommended to reduce microbial accumulation and prevent pathogen growth on contact surfaces.