Bioaccumulation on HVAC filters in university buildings in Singapore

Particle filters are important components of HVAC systems. Biomass accumulation on HVAC filters can potentially have adverse effects on building occupants. The research reported in this paper aims to quantitatively describe the content of biomass on HVAC filters from various indoor office environments in Singapore in relation to key governing processes. In this initial phase, filter samples were collected and analysed using DNA-based methods. The collected DNA was directly extracted from the filters and the final concentration was measured with Qubit and qPCR methods. The DNA concentrations were then related to the cumulative indoor occupancy level. The results show good correlations between bacterial DNA and cumulative occupancy. The proportion of total DNA that belongs to fungal and bacterial species decreases as occupancy level increases, probably because of biomass from other sources such as human skin cells.