A Comparison of Outdoor Bioaerosol and Particulate Measurements in Las Vegas

The urbanization of the Las Vegas Valley has turned the desert into a green oasis by introducing many non-native plant species, some of which are allergenic. Outdoor bioaerosols consist of microorganisms, pollen, spores, and other agents that could cause infections or affect the health of humans. Studies have suggested that exposure to bioaerosols through inhalation can lead to various human health risks. Typically, one monitoring station is established per city to obtain pollen and mold counts for an entire metropolitan area, and the site may not be representative of community exposures. The objective of this study was to measure and compare pollen, mold, bacterial DNA, fungal DNA, and particulate matter concentrations at five locations in Las Vegas to determine if there are differences between microenvironments within the city. Air samples were collected from five sites across the Las Vegas Valley over a one-year period. Samples were collected in 2015, and analyzed for six air quality parameters: pollen counts, mold spore counts, total bacterial and fungal DNA concentrations, and fine and coarse particulate matter (PM2.5 and PM10). A mixed-model analysis was used to examine potential differences. A non-parametric Kendall’s tau correlation was used to examine potential associations between mold spore microscopy counts and total fungal DNA. There were several differences among sites with respect to concentrations of individual tree pollen species. Differences were also observed between the sites for total weed and grass concentrations. Smuts (basidiomycetes) were the dominant spores for all five sites during the spring season. Cladosporium was the second dominant spore with the highest concentrations occurring during the summer and fall months. Overall bacterial DNA concentrations were the highest bioaerosol measurements, with the highest concentrations observed during the winter. The variability among the sites could be due to the differences in geography and landscaping practices near the sampling sites. The results provide bioaerosol measurements for one year in Las Vegas, which may lead to a better characterization of ambient bioaerosols and how they relate to outdoor air quality and human exposure