“The aerobiome in a hospital environment: Characterization, seasonal tendencies and the effect of window opening ventilation”

The urban atmosphere carries biological particles (bioaerosols) that may cause several diseases and allergies. These bioaerosols infiltrate and mix with those present inside the buildings, including hospitals. However, little is known about the behavior of these particles around health facilities. Here, we described the bioaerosols composition of an urban hospital indoor and outdoor at two different periods (winter and summer) using DNA sequencing. We observed that the seasonality and composition of the bioaerosols outdoor was also displayed indoor, and, in some cases, the taxa showed different trends depending on the season. Pathogenic species of bacteria and fungi were found indoors at low levels but also outdoors, being mostly environmental species, which would reject the idea that hospitals may be acting as a source of emission via aerosols. Skin-related bacteria were the most prevalent group related to human microbiome, being more abundant indoors. Air temperature was the principal factor affecting the bioaerosols composition in the samples but, in general, meteorological parameters outdoors were poor descriptors of the bioaerosols indoors. Similarly, the concentrations of the main indoor air pollutants did not correlate with microbial abundances. Globally, natural ventilation through a window opening did not significantly alter the composition of the bioaerosols indoor.