1. Clinical characteristics of the study population and prevalence of PFAS
Of the 930 children, 44 (4.7%) had PFAS, and the mean age of onset was 6.74 years (Table 1). The mean age of the PFAS group was older than that of the non-PFAS group, whereas the rate of breastfeeding was significantly higher in the non-PFAS group compared with the PFAS group. The prevalences of AR and AC in the study population were 48.9% and 16.5%, respectively (Figure 1). Pollen sensitization rate of the study population was 11% (Figure 1) and common in birch, oak, and alder (in order of frequency). Depending on comorbidity, the prevalence of PFAS was 7.2% among children with AR and 19.1% among children with pollinosis (Figure E2).