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

Table 5 Comparison of the subjects with normal spirogram, possibly restrictive, obstructive or mixed pattern for both groups¹

Period of time		Spirogram pattern n (%)
		Normal	Restrictive	Obstructive	Mixed
Before exposure, at the start of the work season	Exposed	40 (87.4)	6 (11.8)	5 (9.8)	0
	Unexposed	45 (88.2)	4 (7.8)	2 (3.9)	0
After exposure, at the start of the work season	Exposed	39 (76.5)	4 (7.8)	8 (15.7)	0
	Unexposed	45 (88.2)	4 (7.8)	2 (3.9)	0
At the end of the work season2	Exposed	27 (53)	6 (11.8)	18 (35.3)	0
	Unexposed	45 (88.2)	4 (7.8)	2 (3.9)	0

¹χ² or Fisher’s exact test; ²significant difference exists between the exposed and unexposed groups (P < 0.001).