The results of spirometry testing at baseline, 6 months and 12 months follow-up are shown in Table II. Spirometry was obtained on all available workers at 6 and 12 months. However, due to logistical issues, spirometry was obtained on only 24 of the 49 (49 %) workers at baseline, and the baseline testing was performed at a different site than the follow-up testing. There were no significant differences in FEV1, FVC and FEV1/FVC comparing baseline, follow-up and the workers lost to follow-up, or when comparing only those workers with spirometry data at all 3 time points (N=16), although there was a trend towards lower FEV1 and FVC values at baseline vs. follow-up in this sub-group (data not shown). Of note, no workers had airflow obstruction (FEV1/FVC < LLN) at baseline, 1 worker (2.4%) had airflow obstruction at 6 months (initial test for that worker) and 2 workers (5.4%) had airflow obstruction at 12 months