Table 4 Comparison of pulmonary function indices by exposure variables.
| Pulmonary function indices | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| FVC/HT2 | FEV1/HT2 | MEF50/HT2 | MEF25/HT2 | FEV1% | ||||||
| Mean (SD) | b (SE)† | Mean (SD) | b (SE)† | Mean (SD) | b (SE)† | Mean (SD) | b (SE)† | Mean (SD) | b (SE)† | |
| Control | 1480 (170) | – | 1220 (160) | – | 1590 (500) | – | 570 (290) | – | 82.6 (7.0) | – |
| Adjusted means and effect of exposure | ||||||||||
| Total | 1520 (170) | 20 (14) | 1270 (160) | 19 (12) | 1660 (470) | 12 (38) | 620 (270) | −4 (19) | 83.9 (6.2) | 0.1 (0.5) |
| Current status* | ||||||||||
| Production | 1500 (190) | 16 (18) | 1240 (190) | 16 (16) | 1570 (490) | −18 (50) | 580 (300) | 5 (25) | 82.7 (6.7) | 0.1 (0.6) |
| Development | 1540 (150) | 37 (20) | 1280 (140) | 33 (17) | 1660 (450) | 15 (54) | 620 (270) | 17 (27) | 83.7 (6.4) | 0.2 (0.7) |
| Maintenance | 1520 (170) | 15 (15) | 1290 (150) | 15 (14) | 1700 (460) | 27 (42) | 630 (250) | −16 (22) | 84.4 (5.8) | 0.1 (0.5) |
| Cumulative status | ||||||||||
| 1–10 | 1530 (170) | 25 (16) | 1300 (170) | 32 (14)‡ | 1690 (480) | 23 (44) | 680 (310) | 33 (22)‡ | 84.9 (6.7) | 0.6 (0.6) |
| 11–20 | 1520 (170) | 22 (15) | 1260 (150) | 15 (13) | 1640 (450) | 11 (42) | 570 (210) | −33 (21) | 83.2 (5.4) | −0.3 (0.5) |
| 21+ | 1420 (150) | −36 (34) | 1150 (140) | −32 (30) | 1460 (500) | −60 (94) | 460 (170) | −17 (48) | 80.9 (6.7) | −0.2 (1.2) |
| Confounders | ||||||||||
| Age | – | −45 (7) | – | −80 (6) | – | −137 (20) | – | −147 (10) | – | −2.9 (0.3) |
| Smoking | – | −7 (10) | – | −21 (9) | – | −74 (28) | – | −44 (14) | – | −1.1 (0.4) |
*Production: toner production; development: machine development; maintenance: machine maintenance.
†Mean: crude mean; SD: standard deviation; b: regression coefficient; SE: standard error.
‡Significantly negative tendency (p<0.01) associated with exposure duration.
Values shown are the crude arithmetic mean (standard deviation) and independent effect for each exposure category after adjustment for age and smoking status, estimated as regression coefficients in analysis of covariance models. The effects of age and smoking as confounding factors in these regression models are also shown.