Table 3

Change in bronchial responsiveness in apprentices 15 months after starting exposure to welding fumes

PC20
2‐fold decrease3.2‐fold decrease
New cases of BHR–/+13 (6.7)13 (6.7)
Cases with deterioration of BHR+/++16 (8.2)10 (5.2)
Total29 (14.9)23 (11.9)
Normalisation of BR+/–6 (3.1)6 (3.1)
No change in BR+/+17 (8.8)23 (11.9)
Normal BR throughout–/–142 (73.2)142 (73.2)
  • Data are presented as n (%)

  • Ten students refused to do the test at the third visit (two of them had not done the test initially at visit 1)

  • PC20: provocative concentration causing a 20% fall in the forced expiratory volume in one second

  • BHR: bronchial hyperresponsiveness

  • BR: bronchial responsiveness

  • –: PC20 >16 mg·mL−1

  • +: PC20 ≤16 mg·mL−1

  • ++: baseline PC20 ≤16 mg·mL−1 and a ≥two-fold decrease in PC20

  • n=194