The lung function impairment is the most common respiratory problem in industrial plants and their vicinity. Therefore, the purpose was to study the affects of wood dust and its duration of exposure on lung function. This was a matched cross-sectional study of Spirometry in 46 non-smoking wood workers with age range 20 - 60 years, who worked without the benefit of wood dust control ventilation or respiratory protective devices. Pulmonary function test was performed by using an electronic Spirometer. Significant reduction was observed in the mean values of Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV1), and Maximum Voluntary Ventilation (MVV) in wood workers relative to their matched controls. This impairment was increased with the duration of exposure to wood industries. It is concluded that lung function in wood workers is impaired and stratification of results shows a dose-response effect of years of wood dust exposure on lung function.