Fig. 4

Relationship between SpO₂ and age in each sex. Age plotted against SpO₂ in participants. Males and females are indicated by blue and red circles, respectively. There was a negative correlation between age and SpO₂ in each sex, and the approximate expressions for males and females were derived as y = − 0.0872x + 94.868 (r = − 0.4034193, p = 0.0003021, blue line) and y = − 0.1147x + 96.136 (r = − 0.6118297, p = 6.615e−12, red line), respectively, using Pearson correlation analysis