Culturable airborne fungi in outdoor environments in Beijing, China

Airborne fungi are being proposed as a cause of adverse health effects. They may adversely affect human health through allergy, infection, and toxicity. Moreover, they have a great influence on urban air quality in Beijing. In this study, a systematical survey on the culturable airborne fungi was carried out for 1 year in Beijing urban area. Fungal samples were collected for 3 min, three times each day, and continued for three consecutive days of each month with FA-1 sampler from three sampling sites. Results showed that the culturable fungal concentrations ranged from 24 CFU (Colony forming units) /m3 to 13960 CFU/m3, and the mean and median was 1165 CFU/m3 and 710 CFU/m3, respectively. Fungal concentrations in the greener area around the Research Center for Eco-Environmental Sciences (RCEES) and Beijing Botanical Garden (BBG) were significantly higher than in the densely urban and highly trafficked area of Xizhimen (XZM) (***P<0.001), but no significant difference was found between RCEES and BBG (P>0.05). The variation of fungal concentrations in different seasons was significant in RCEES and BBG, where the concentrations were higher in Summer and Autumn, and lower in Spring and Winter. However, there were no significant differences in fungal concentrations between the Spring and the Winter for three sampling sites (P>0.05). Fourteen genera, including 40 species of culturable fungi, were identified in this study. Penicillium, with the most abundant species, which comprised more than 50% of the total isolated fungal species. Cladosporium were the most dominant fungal group, and contributed to more than one third of the total fungal concentration, followed by non-sporing isolates, Alternaria, Pencillium and Asperigillus. The concentration percentage of Cladosporium was significantly higher in RCEES than in XZM (*P<0.05), and the concentration percentages of Penicillium (**P<0.01) and Aspergillus (*P<0.05) were higher in XZM than in RCEES and in BBG. For other groups' concentration percentages, no significant differences were observed among the sampling sites. The distribution pattern of airborne fungi presented log-normal distribution. The highest proportion of culturable fungi was detected in stage 4 (2.0-3.5 μm), and the lowest was in stage 6 (<1.0 μm).