Table 4. Associations between lifetime occupational exposures and DLCO, stratified according to smoking history.

Exposure Category		Former Smokers Long-term quitters>10 years (n = 93)		Formers Smokers Short-term quitters≤10 years (n = 104)		Current smokers (n = 145)
		Coefficient (95% CI)	P value	Coefficient (95% CI)	P value	Coefficient (95% CI)	P value
Lifetime high exposure to	Biological dust	18.0 (0.7, 35.4)	0.042	−5.1 (−23.5, 13.2)	0.576	2.2 (−8.5, 12.8)	0.687
	Mineral dust	22.2 (10.0, 34.4)	0.001	−3.5 (−16.1, 9.0)	0.573	4.0 (−7.12, 15.2)	0.476
	Gases or fumes	14.6 (−0.4, 29.6)	0.057	10.1 (−0.6, 20.8)	0.065	5.6 (−3.7, 14.9)	0.233

Linear regression models adjusted for sex, age, age2, weight and pack-years smoked. The reference category for all comparisons included participants with no history of high exposure to biological dust, mineral dust, or gases/fumes (n = 110; see Table 2).