Figure 1.

Ordination diagram (axis 1 and 2 from a NMDS ordination) summarizing similarity of airborne bacterial community composition (weighted UniFrac community phylogenetic dissimilarity) in samples from outdoors (blue), indoor mechanically ventilated patient rooms (red) and indoor window-ventilated patient rooms (green) at a health-care facility. Distances among communities indicate the phylogenetic similarity of bacteria in those communities. Symbols indicate sample location (○=room 229, □=room 231, ◊=room 235 and △=roof; Supplementary Table S1). Ellipses are 95% confidence intervals around samples from each environment. Arrows indicate direction of correlation between axis 1 scores from the NMDS ordination versus relative humidity (% r=0.67, P=0.01), temperature (°C; r=−0.68, P=0.01) and air flow velocity (m s⁻¹; r=0.50, P=0.07).