Temporal variation of airborne fungi in university library rooms and its relation to environmental parameters and potential confounders.

Indoor airborne fungi have been associated with adverse human health effects. Therefore, it is important to understand the causes of underlying variation in airborne fungi in indoor environments. This study consequently aimed to investigate the association between indoor fungi with temporal variation, environmental parameters, and potential confounders over 10 months in four library rooms using Andersen samplers. Indoor fungal concentrations peaked in October and were lowest in March in both stack rooms, whereas the highest concentrations in both reading rooms were observed in September with lowest concentrations in July. Nonparametric analyses revealed higher fungal concentrations in the rooms that were significantly associated with relative humidity ≥ 60%, PM ≥ 35 μg/m, number of people ≥ 16, open windows, working air conditioners, and room area < 400 m. Multiple linear regression modeling for the library building considering only continuous variables revealed that relative humidity, PM, and the number of people were significant predictors of fungal concentrations. Additionally, the model with continuous and categorical variables suggested that relative humidity, PM, the number of people, ceiling fan condition, window state, and air conditioner operating status were significant predictor variables of concentrations. Outdoor fungal concentrations were a significant predictor for the two models of indoor fungal concentrations for each room. Ceiling fan or air conditioner operation was associated with altered fungal particle concentrations. These results provide a deeper understanding of indoor air fungal quality.