Spirometric standards of Libyan boys and girls.

Ventilatory capacities of 578 Libyan boys and 527 Libyan girls aged between 12 and 21 years were measured. The data of forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were analyzed by logarithmic regressions on age, standing height (stature), sitting height, body mass index and body surface area. The prediction formulae for pulmonary function in Libyan boys and girls were calculated. Standing height (stature) appears to be marginally better than sitting height as an index of body size in explaining the variance in ventilatory capacity of Libyan boys and girls. Libyan boys and girls have a greater proportional leg length than their British counterparts. Their mean values of FVC and FEV1 are lower than those of British children by about 13%. About 10% of Libyan boys are smokers. Below 14 years of age, there were no smokers. A steady rise in number of smokers from the age of 14 years reaching 41% at 21 years of age was observed. No smokers were reported from the Libyan girls. There was no statistically significant difference in the mean FVC or FEV1 between the smokers and nonsmokers.