AbstractBackground: Closed building syndrome affects pulmonaryfunction.Aim of Study: This study aimed to identify the effect ofclosed building syndrome on pulmonary function.Subjects and Methods: Eighty switch workers men withclosed building syndrome were included in this study. Theirage ranged from thirty to forty years old. They were recruitedfrom from El-Kasr El-Ainy University Hospital. Beforeinclusion in this study full description of study, proceduresfor each patient and written consent had been signed. All menpatients were evaluated with ventilatory function testing andarterial blood gases.Results: The mean values of age (year), weight (kg),height (cm), and BMI (kg/m2) were 34.34±3.11, 74.02±8.00,168.67±5.96, and 26.02±1.90, respectively in study group.Number (percentage) of normal and abnormal (hypoxic)arterial blood gases distributions were 77 (96.3%) and 3 (3.8%), respectively. Number (percentage) of normal, obstruc-tive and restrictive R. functions distributions were 54 (67.5%),11 (13.7%), and 15 (18.8%), respectively. The mean value oftotal working was 83.91±14.75 hours with minimum andmaximum values 6720.00 hour and 26880.00 hour, respec-tively. The mean value of respiratory functions was 87.09±14.38% with minimum and maximum values 60.20% and103.3%, respectively. There was strong negative correlationbetween total working time and respiratory functions (r=–0.68; p=0.0001; p < 0.05). There was strong negative correlationbetween total working time and respiratory functions. Theresults showed that there was significant relation betweenworking time and respiratory functions also, this means thatchange in the respiratory functions are consistent with changein total working time.Conclusion: There were significant relation betweenworking time and respiratory functions.