Aerosol fluorescence, airborne hexosaminidase, and quantitative genomics distinguish reductions in airborne fungal loads following major school renovations.

Fluorescent aerosol cytometry (FAC) was compared to concurrent recovery of airborne β-N-acetylhexosaminidase (NAHA) and quantitative polymerase chain reaction (qPCR) for the respective ability of these methods to detect significant changes in airborne fungal loads in response to building renovations. Composite, site-randomized indoor aerosol samples for airborne fungi measurements were acquired from more than 70 occupied classrooms in 26 different public schools in the Colorado Rocky Mountain Front Range region of the United States. As judged by ANOVA and Pearson's correlation test, statistically significant associations were observed between real-time FAC and airborne NAHA levels, which detected significant reductions in airborne fungal loads immediately following building rehabilitations. With lower confidence, a statistically significant association was also resolved between fluorescing aerosols, NAHA levels, and the recovery of fungal 18S rRNA gene copies by qPCR from simultaneous, collocated aerosol samples. Quantitative differences encountered between the recovery of common genomic markers for airborne fungi and that of optical and biochemical methods are attributed to the variance in 18S rRNA target gene copies that different fungal species can host.