Theresa T Roehr, Patricia Cruz, Asma Tahir, Mark P Buttner, Steven Medley
Quantitative assessment of airborne fungi is essential for environmental monitoring and public health. However, methodological differences can substantially influence the concentrations reported. This study compared microscopic enumeration and quantitative polymerase chain reaction (QPCR) for measuring total airborne fungal concentrations in Las Vegas, where regional data remain limited. Air samples were collected from January to December 2022 using volumetric spore samplers for microscopic analysis from five permanent sites and portable filtration samplers for QPCR analysis from 13 nearby sites. Microscopic analysis was performed at 1000× magnification following National Allergy Bureau protocols, while QPCR targeted a highly conserved region in the fungal rDNA gene using a validated universal fungal PCR assay. Overall, mean total fungal concentrations measured by QPCR were approximately seven times higher than those obtained by microscopy. Seasonal comparisons showed different results between methods, with higher concentrations in spring and summer and lower levels in winter measured with QPCR and higher concentrations in winter and lower levels in summer obtained with microscopy. The difference in concentration between methods was statistically significant. The higher concentrations detected by QPCR likely reflects the use of a multicopy gene as the target sequence, whereas microscopy may underestimate total fungal burden due to interference from non-biological particulates. These findings highlight important methodological considerations in airborne fungal monitoring and support the integration of molecular techniques to enhance environmental health surveillance.