Table 4. Adjusted differences between ever- and never-smokers, people with and without asthma, and people with and without COPD, by quartile of long-term (30 year) time-weighted average H₂S exposure.

Spirometric measure	H2S Quartile	Difference (liters) a
		Smoking b	Asthma c	COPD c
FEV 1	1	−0.36	−0.36	−0.97
	2	−0.24	−0.38	−0.66
	3	−0.20	−0.29	−0.77
	4	−0.11	−0.34	−0.72
	P for trend	0.09	0.75	0.30
FVC	1	−0.33	−0.26	−0.64
	2	−0.19	−0.31	−0.37
	3	−0.08	−0.28	−0.35
	4	−0.10	−0.28	−0.34
	P for trend	0.15	0.99	0.23
FEV 1/FVC	1	−0.050	−0.078	−0.190
	2	−0.033	−0.062	−0.146
	3	−0.040	−0.029	−0.155
	4	−0.013	−0.051	−0.156
	P for trend	0.07	0.10	0.19
FEF 25–75	1	−0.43	−0.62	−1.41
	2	−0.34	−0.62	−1.17
	3	−0.52	−0.32	−1.29
	4	−0.12	−0.53	−1.34
	P for trend	0.18	0.44	0.99

^a (measure with condition, e.g., ever-smoking)–(measure without condition e.g., never-smoking).

^b Adjusted for age, sex, income, education, and Polynesian race.

^c Adjusted for age, sex, income, education, Polynesian race, and smoking status.