Fig. 1From: Spirometric reference equations for Cameroonians aged 4 to 89 years derived using lambda, mu, sigma (LMS) methodRelationship between spirometric indices and age in males (A, B, C, D) and females (E, F, G, H) after natural logarithmic transformation. FEV1, forced expiratory volume in 1 s (FEV1); FVC, forced vital capacity; FEF25-75%, forced mid-expiratory flowBack to article page