Additionally, at 6 months follow-up no workers had a decrease in FEV1 of > 15% and 6 /19 (31.6%) showed an increase in FEV1> 15%, consistent with lower spirometry values noted at baseline. At 12 months follow-up, a decrease in FEV1 of > 15% was measured in 3 workers (9.1%) between 6 and 12 months follow-up, one of whom reported new asthma symptoms. Three workers exhibited an increase in FEV > 15% between 6 and 12 months