Pulmonary effects of intermittent, seasonal exposure to high concentrations of cotton dust

Table 3 Changes in pulmonary function test parameters of the exposed and unexposed subjects

Parameters	Exposed workers (n = 51)					Referent group
	Preshift1	Postshift1	End of season2	End of shift end of workweek3	After 48 h of exposure free period4	(n=51)
VC	78.9 ± 16.3b	76.6 ± 17d	73.2 ± 16.6f	78.8 ± 16.3h	76.1 ± 16.3	85.5 ± 13.5
FVC	84.8 ± 12.6b	85.2 ± 12.9	86.2 ± 16.5	85.5 ± 12.8	84.8 ± 12.6	81 ± 4.4
FEV1	79.7 ± 13.7b	78.3 ± 12.4d	74.6 ± 13.1f	76.7 ± 11.7h	79.1 ± 13.7	90.1 ± 10.5
FEV1/FVC	94.1 ± 14.5b	89.3 ± 20.2	89.3 ± 20.2	90.6 ± 12h	94.1 ± 14.5	107.6 ± 14.5

¹At the beginning of work season (prior to and end of first shift of workweek);

²At end of the work season;

³At end of shift at end of workweek;

⁴48 h after exposure ceased;

^bP < 0.05 vs the referent group;

^dP < 0.05 vs preshift;

^fP < 0.05 vs preshift;

^hP < 0.05 vs after 48 h of exposure free period. VC: Vital capacity; FVC: Forced vital capacity; FEV: Forced expiratory volume.