Table 2

Cohort characteristics and distribution of obstructive lung diseases as underlying (OLD-u) and underlying or contributing (OLD-uc) cause of death 1951–2007, for 1687 male long-term workers in the Norwegian silicon carbide industry employed 1913–2003

	N	Person-years	OLD-u	OLD-uc
Year of birth
Before 1920	513	12 960	24	40
1920–1939	418	12 932	21	27
1940–1959	483	12 769	0	0
1960–1980	273	4028	0	0
Year of first employment
Before 1940	185	4668	6	9
1940–1959	295	9941	14	24
1960–1979	770	21 108	25	34
1980–2000	437	6972	0	0
Year of death
1951–1969	96	1006	2	3
1970–1989	309	6507	12	15
1990–2007	383	12 133	31	49
Alive	899	23 042	–	–
Smoking
Never-smokers	359	9187	3	8
Ever-smokers	1162	30 474	38	55
Unknown	166	3028	4	4
Department affiliation
Furnace	386	9226	13	20
Processing	346	7751	9	15
Maintenance	314	7978	4	7
Low exposed	175	5012	1	1
Mixed	466	12 723	18	24