Fig. 3

Comparison of alpha diversities (the number of ASVs) of nasopharyngeal swabs. Nasopharyngeal swabs collected in the morning and in the afternoon (after an 8 h exposure to the workplace environment) were grouped according to participants’ workplaces; maternity hospital (NEO; n = 8), pediatric hospital (ENT; n = 5), and a research center (RCX; n = 8). Morning and afternoon samples were compared using the Wilcoxon signed-rank test (p > 0.05). One nasopharyngeal sample (from a participant working at ENT) collected in the afternoon was excluded from the analysis due to the low DNA conent in the sample