TABLE 2.

MEANS (SD) OF ΔFEV₁ IN THREE SURVEYS AMONG COTTON AND SILK GROUPS

	Cotton			Silk
	N	ΔFEV1 (ml)	ΔFEV1 (%)	n	ΔFEV1 (ml)	ΔFEV1 (%)
1981	391	−57.9 (154.9)*	−1.98 (5.49)*	376	−5.6 (131.9)	−0.02 (4.82)
1986	284	−47.8 (135.3)†	−1.77 (6.62)†	307	−26.1 (115.9)	−0.87 (4.22)
1992	222	−54.2 (120.9)‡	−1.87 (4.42)§	225	−20.2 (98.9)	−0.69 (3.78)
1996	119	−66.6 (141.5)	−2.15 (5.51)	0	—	—

Definition of abbreviation: ΔFEV₁ = cross-shift change in FEV₁.

Calculations are based on all available data at each survey.

^*P < 0.0001.

^†P = 0.04.

^‡P = 0.001.

^§P = 0.003 in comparison with silk workers.