[Table/Fig-1]:

Baseline Characteristics of Cases and Controls

Characteristics			Cases			Controls
	Range	Mean	SE	95% CI	Range	Mean	SE	95%CI
Age (Years)	22-52	32.20	0.97	30.2-34.1	21-52	33.22	1.02	31.1-35.2
Work (Years)	2-25	8.36	0.72	6.9-9.8	1-30	10.00	0.91	8.1-11.8
Smoking (Years)	0-10	3.12	0.49	2.1-4.1	0-20	4.08	0.81	2.4-5.7
Cigarettes/day	0-12	2.84	0.46	1.9-3.7	0-12	1.82	0.43	0.9-2.6
Respiratory Symptoms (years)	0-7	2.72	0.31	2.0-3.3	0-10	1.04	0.35	0.3-1.7
Hemoglobin (g/dL)	11-17	14.42	0.17	14.0-14.7	11-22	13.64	0.34	12.9-14.3
FEV1/FVC ratio (%)	59-82	69.24	0.78	67.6-70.8	64-80	71.90	0.64	70.6-73.1
FEV1%	50-85	72.86	1.50	69.8-75.8	58-86	78.48	0.98	76.5-80.4
RDW%	12.2-18.8	15.89	0.23	12.2-18.8	12.3-17.8	14.28	0.21	13.8-14.7