Cox regression models: Hazard ratios for CWP ≥ 0/1 and cumulative exposure to respirable coal mine dust, or mean concentration and exposure duration, and covariables. No. of subjects = 1369, No. of cases = 72.

Table 3: Cox regression models: Hazard ratios for CWP ≥ 0/1 and cumulative exposure to respirable coal mine dust, or mean concentration and exposure duration, and covariables. No. of subjects = 1369, No. of cases = 72.

Covariable	Haz. ratio	Std. err	95% CI		P > \|z\|
Approach 1
Cumulative coal mine dust (mg/m³-years)	1.014	0.008	0.999	1.031	0.074
Height (cm)	0.994	0.020	0.956	1.033	0.753
Weight (kg)	1.020	0.008	1.004	1.036	0.015
Non-german nationality^**	1.695	0.335	0.880	3.268	0.115
Coking coal^**	1.190	0.274	0.696	2.034	0.525
Active smoker^**	1.782	0.324	0.944	3.363	0.075
Former smoker^**	1.016	0.398	0.466	2.215	0.968
Approach 2
Mean concentration of coal mine dust (mg/m³)	0.997	0.198	0.676	1.471	0.988
Exposure duration (year)	1.082	0.033	1.014	1.154	0.017
Height (cm)	0.993	0.020	0.955	1.033	0.732
Weight (kg)	1.019	0.008	1.003	1.036	0.023
Non-german nationality^**	1.733	0.338	0.894	3.358	0.103
Coking coal^**	1.324	0.279	0.766	2.287	0.314
Active smoker^**	1.696	0.323	0.900	3.196	0.102
Former smoker^**	0.935	0.399	0.428	2.043	0.866

Statistics: Hazard ratio with standard error; Wald test: z-value, Two-sided p-value; CI: Confidence interval.

^**Reference: German nationality; Gas and flaming coal; Non-smoker.