Abstract: Objective To establish predictive equations of lung function for adults in urban areas in north China. Methods A
survey was conducted in 600 male and 600 female healthy adults in the urban areas in north China. Five flow-volume test
parameters were measured including forced vital capacity (FVC) and forced expiratory volume in one second (FEV1).
Stepwise multiple regression was carried out to establish the predicative equations for the parameters for male and female
adults separately. The predicted values from these equations and those from other commonly used equations (such as ECCS
equation and Knudson equation) were compared with the actual measurements in pulmonary function tests. Results Four
flow-volume test parameters, namely FVC, FEV1, 25% forced expiratory flow (FEF25% ), and FEF75% , showed obvious
differences between the male and female adults, while FEV1/FVC was not correlated with gender. Multiple regression analysis
showed that FVC, FEV1, FEF25% and FEF75% were positively correlated with height and negatively with age, and FEV1/FVC
was negatively correlated with both height and age. The parameters were not affected by body weight. The predicted values
from our equations were closer to the actual measurements than those calculated from other equations. Conclusion The
equations we established are more appropriate than the generally used equations for predicting lung functions in adults in
north China urban areas.