In accordance with our previous study (10), the strong relationship between across-shift drops in FEV1 and longitudinal losses of pulmonary function is reconfirmed in the current study.
Across-shift changes in FEV1 were associated with a loss of 916 ml in FEV1 and 678 ml in FVC over 15 yr among the cotton workers, irrespective of respiratory symptoms, and the changes
were significant. It is assumed that across-shift drops in FEV1 and chronic airway obstruction are not a causal relationship, and both may be a consequence of exposure to cotton dust.