KiwiRail says it is confident the level of risk from exposure to airborne asbestos in its Chinese- made locomotives is minimal, following results from the second round of testing.
The company says seven out of the 204 samples taken showed a very small presence of non-respirable asbestos in five of the locomotives. It found no presence of any asbestos dust in the remaining 34 locomotives.
KiwiRail removed 40 freight trains from service at the end of February this year after the manufacturer confirmed that highly toxic material had been sprayed on metal sheeting.
While testing was underway, asbestos was also found in the doors.
KiwiRail chief executive Peter Reidy said the company is confident that measures can be put in place to bring the locomotives back into service soon.