Figure 1

Forced expiratory volume in one second (FEV1) versus forced vital capacity (FVC) in females and males. Light gray dots – the studied material; thin lines – the linear regression; bold points creating curves – the moving 50th percentile of FEV1 for particular values of FVC calculated separately in three ranges of age (blue- 18–40, black- 41–65, and red- 66–85 years).