Table 5. Effects of duration of experience/exposure on participants’ pulmonary function test values.
| Exposure duration (years) (participants, n) |
FEV1 (L),
median (range) |
FVC (L),
median (range) |
FEV1/FVC (%),
median (range) |
PEFR (L/min),
median (range) |
| 1 - 5 (50) | 3.2 (2.05 - 3.97) | 3.43 (2.32 - 6.18) | 93 (50 - 100) | 379 (192 - 506) |
| 6 - 10 (10) | 3.06 (2.32 - 3.59) | 3.35 (2.6 - 3.96) | 91.5 (76 - 93) | 337.5 (163 - 500) |
| 11 - 15 (7) | 2.36 (2.12 - 2.86) | 2.61 (2.41 - 3.12) | 90 (80 - 82) | 285 (170 - 310) |
| 15 (25) | 2.19 (0.43 - 3.3) | 2.6 (0.52 - 3.58) | 84 (61 - 100) | 310 (115 - 410) |
| p-value | 0.001* | 0.001* | 0.001* | 0.001* |
| Exposure duration (years) (participants, n)† | Parameter | Exposed (n=92), mean (SD) | Matched group (n=92), mean (SD) | p-value |
|
| ||||
| 1 - 5 (50) | FEV1 (L) | 3.04 (0.49) | 3.19 (0.33) | <0.001‡ |
| FVC (L) | 3.32 (0.65) | 3.47 (0.38) | <0.001‡ | |
| FEV1/FVC (%) | 91.56 (7.9) | 91.93 (0.15) | 0.574 | |
| PEFR (L/min) | 384.18 (74.66) | 477.2 (57.47) | <0.001‡ | |
| 6 - 10 (10) | FEV1 (L) | 3.0 (0.46) | 3.18 (0.41) | 0.36 |
| FVC (L) | 3.29 (0.47) | 3.47 (0.44) | 0.005‡ | |
| FEV1/FVC (%) | 91.18 (5.28) | 91.64 (1.94) | 0.311 | |
| PEFR (L/min) | 371.9 (109.77) | 462.4 (78.51) | 0.007‡ | |
| 11 - 15 (7) | FEV1 (L) | 2.38 (0.24) | 2.63 (0.37) | 0.075 |
| FVC (L) | 2.69 (0.24) | 2.87 (3.8) | 0.063 | |
| FEV1/FVC (%) | 88.4 (4.1) | 91.63 (2.08) | 0.072 | |
| PEFR (L/min) | 269.29 (49.15) | 358.23 (48.11) | 0.018‡ | |
| 15 (25) | FEV1 (L) | 2.12 (0.69) | 2.8 (0.41) | <0.001‡ |
| FVC (L) | 2.56 (0.76) | 3.09 (0.41) | 0.002‡ | |
| FEV1/FVC (%) | 82.81 (10.47) | 90.61 (3.78) | <0.001‡ | |
| PEFR (L/min) | 289.04 (93.17) | 404.96 (90.74) | <0.001‡ | |
FEV1 = forced expiratory volume in 1 second
FVC = forced vital capacity
PEFR = peak expiratory flow rate
SD = standard deviation
* Significant (p<0.05) according to the Kruskal-Wallis test.
† Years of education and employment in the matched unexposed group were adjusted to match the years of experience/exposure in the exposed group
‡ Significant (p<0.05) according to the Mann-Whitney U-test