Assessment of microbial contamination of indoor air

Min Manwayk Sorn

Bachelor's thesis

Abstract:

This study evaluates the efficacy of the Omeliansky sedimentation technique for monitoring indoor microbial air quality within university facilities. The research investigated the influence of two cultivation media, Tryptic Soy Agar (TSA) and Nutrient Agar (NA), across exposure durations of 8, 12, and 24 hours. Sampling was conducted across diverse functional zones at CZU Prague, including classrooms, student lounges, and toilets. Statistical analysis using ANOVA and Welch’s t-tests revealed that location was the primary driver of microbial variance, identifying toilets and high-traffic lounges as significant hotspots (p < 0.05). While both media performed comparably in low-load environments, TSA demonstrated superior recovery of diverse microbial communities in highly contaminated zones. Results indicate that an 8-hour exposure window provides the most reliable volumetric estimation, as 24-hour sampling led to significant underestimation due to agar desiccation and inter-colony competition. These findings validate the sedimentation method as a robust screening tool for indoor environments and support the implementation of risk-based maintenance protocols and standardized 8-hour sampling windows to ensure data integrity.

Keywords

agar, humidity, exposure, microbial, sedimentation, contamination

Jazyk práce: English

Datum vytvoření / odevzdání či podání práce: 1. 4. 2026

Obhajoba závěrečné práce

• Vedúci: doc. Ing. Lenka Wimmerová, MSc Ph.D.
• Oponent: Martin Halecký, externi

Czech University of Life Sciences Prague

Faculty of Environmental Sciences

Bachelor programme:
Environmental Engineering