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

Table 2 Frequency (%) of respiratory symptoms in the exposed and unexposed subjects¹n (%)

Symptoms	Exposed	Unexposed
	(n = 51)	(n = 51)
Cough	19 (37)b	2 (4%)
Phlegm	19 (37)b	4 (8%)
Productive cough	4 (8)	0
Wheezing during a cold	21 (41)b	5 (10%)
Wheezing apart from colds	14 (27)b	3 (6%)
Wheezing accompanied by Shortness of breath	7 (14)d	0
Shortness of breath	8 (16)d	1 (2%)
Byssinosis grade 1/2	9 (17.6)b	0
Byssinosis grade I	3 (6)	0
Byssinosis grade II	2 (4)	0

¹χ² or Fisher’s exact test;

^bP < 0.001;

^dP < 0.01.