Table 3. Incidence rates of causes of death among the subjects stratified by the status of second hand smoking (SHS) (N = 161,609).

	No SHS exposure		Mild SHS exposure		Heavy SHS exposure			Mild vs No	Heavy vs Mild	Heavy vs No
Characteristics	No (N = 72,009)(PYs = 866,081.34)		>0, < = 20 cigarettes (N = 78,421)(PYs = 942,235.54)		> 20 cigarettes(N = 11,179)(PYs = 134,227.33)		Overall p a
Cause of deaths	N. of deaths	Incidence	N. of deaths	Incidence	N. of deaths	Incidence
Total mortality	324	37.4	480	50.9	91	67.8	<0.001***	<0.001***	0.011*	<0.001***
Unnatural death	240	27.7	367	38.9	77	57.4	<0.001***	<0.001***	0.002**	<0.001***
Accident	196	22.6	299	31.7	57	42.5	<0.001***	<0.001***	0.039*	<0.001***
Suicide	32	3.7	55	5.8	17	12.7	<0.001***	0.036*	0.004**	<0.001***
Homicide	4	0.5	6	0.6	1	0.7	0.850	0.617	0.883	0.666
Undetermined for unnatural deaths	8	0.9	7	0.7	2	1.5	0.674	0.674	0.376	0.541
Natural death	84	9.7	113	12.0	14	10.4	0.355	0.153	0.642	0.797
Cancer	35	4.0	36	3.8	3	2.2	0.608	0.815	0.365	0.318
Endocrine or Metabolic	5	0.6	4	0.4	0	0.0	0.639	0.644	0.451	0.379
Neurological	2	0.2	3	0.3	1	0.7	0.608	0.723	0.450	0.312
Cardiovascular	8	0.9	13	1.4	3	2.2	0.381	0.367	0.449	0.178
Respiratory	1	0.1	6	0.6	1	0.7	0.186	0.075	0.884	0.130
Gastrointestinal	4	0.5	3	0.3	0	0.0	0.678	0.624	0.514	0.431
Genitourinary	4	0.5	2	0.2	0	0.0	0.508	0.358	0.594	0.431
Skin	3	0.3	4	0.4	1	0.7	0.796	0.787	0.612	0.497
Bone	0	0.0	6	0.6	0	0.0	0.041*	0.019*	0.355	-
Others	8	0.9	12	1.3	1	0.7	0.716	0.476	0.604	0.843
Undetermined for natural deaths	14	1.6	24	2.5	4	3.0	0.358	0.209	0.714	0.267

^a. testing by means of life tables analysis

*: p<0.05,

**: p<0.01,

***:p<0.001