Table IV.

Correlation of cumulative total dust exposure and cumulative abnormal rate of pulmonary function in smoking subgroup.

Cumulative total dust exposure (mg/m3 years)	Subject no. at the beginning of the period	Subject no. at the end of the period	Morbidity	Abnormal rate	Accumulative abnormal rate
0	200	0	0	0.0000	0.0000
100	200	7	1	0.0051	0.0054
200	193	6	1	0.0053	0.0103
300	187	6	2	0.0109	0.0161
400	181	8	3	0.0169	0.0276
500	173	10	4	0.0238	0.0404
600	163	8	3	0.0189	0.0422
700	155	9	4	0.0266	0.0449
800	146	9	5	0.0353	0.0610
900	137	14	7	0.0538	0.0873
1,000	123	13	8	0.0687	0.1188
1,100	110	21	11	0.1106	0.1716
1,200	89	19	11	0.1384	0.2336
1,300	70	23	12	0.2051	0.3151
1,400	47	17	13	0.3377	0.4735
1,500	30	15	10	0.4444	0.6320
1,600	15	6	4	0.3333	0.6296
1,700	9	9	3	0.6667	0.7778