Wood dusts may have substantial health impacts beyond those of nuisance dust. This project reports results linking pulmonary function changes with exposure to maple and pine dust. A cross-sectional survey of 1157 woodworkers was conducted in 1978 in accordance with NHLBI standards for respiratory epidemiologic surveys. Area dust levels were determined, permitting definition of groups exposed to estimated high, medium or low cumulative levels of dry hardwood or softwood dust. Prevalence of reduced (lower fifth percentile of normal) pulmonary function was ascertained, using prediction equations, for Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 second (FEV1), FEV1/FVC and Maximal Mid-expiratory Flow Rate (MMEFR). Relationships between pulmonary impairment and dust exposure were examined, adjusting for smoking status by means of the log odds ratio method. The results support an association between dry hardwood or softwood dust exposure and reduced pulmonary flow rates. The odds ratios for reduced pulmonary function, comparing low and high hardwood (maple) dust exposure, were 3.12 for FEV1/FVC and 2.14 for MMEFR. Comparing low and medium hardwood exposure, the odds ratios were 2.61 for FEV1/FVC and MMEFR. Comparison of low and high softwood (pine) dust exposure yielded odds ratios of 4.03 for FEV1/FVC and 2.45 for MMEFR. The ratios noted are significant at p less than .05.