The impact of renovation on indoor airborne bacterial and fungal populations

Abstract

We undertook an extensive study of population and type of viable microorganisms at several indoor construction sites in a 50-year-old chemical building which housed both laboratory and office spaces. Results were compared to neighbouring public buildings (office and shopping malls), as well as outdoor (green areas and traffic zones) in downtown Montreal, (45 °30′N, 73 °35′W). The highest number of microorganisms was observed in the major shopping street (bacteria: 602,865 cfu/m3; fungi: 109,612 cfu/m3). During moving/construction process, the mean population of airborne bacteria and fungi were 89,281 and 50,386 cfu/m3, respectively. Mean bacterial and fungal population in demolished laboratory sites were 37,127 and 17,679 cfu/m3, respectively. After the termination of laboratory renovations, continued elevation of airborne taxa population (bacteria: 25,635 cfu/m3; fungi: 6188 cfu/m3) was observed. At the construction site, the 16S rDNA sequence of bacteria isolates, R. equi, was identified as human pathogen and R. jostii RHA1 in an organic demolished laboratory site, with the ability to degrade a variety of xenobiotic compounds such as polychlorinated biphenyls. Our study showed that renovation/construction activities could create a distinct large pool of microorganisms that could be released into indoor environments which may persist even after the completion of renovations. Potential health effects and suggestions for future research are discussed in this paper.