HEATERS on most of Merseyrail’s trains were turned off last week while the operator waited for the results of tests for asbestos.
Concerns were raised by a trade union safety official on Wednesday.
But the company said test results came back all clear and the heaters are now working normally again.
Heaters in all Merseyrail’s trains, some of which are 34-years-old, contain white asbestos.
Merseyrail and the RMT union said there is no danger to passengers during normal running of the heaters.
But Merseyrail spokesman Rudi Boersma revealed that a trade union safety representative brought an asbestos-related issue to their attention during the week.
He said heaters on a number of trains operating “bellows-type” heating units were switched off and experts were brought in immediately to take test samples.
He said: “The results came back within 48 hours and there was no hint of asbestos.”
He added: “We would never expose any of our staff or passengers to any danger.
“We are zero tolerant to any risks and after we got the all clear the heating is back on and operating as normal.”
Mr Boersma could not confirm how many trains were affected but an insider told the ECHO that up to two thirds of its 55-strong fleet were tested.
The RMT played down the incident, but the union did raise concerns a year ago about the potential danger of asbestos to its fitters during major overhauls of the ageing heating units.
Shortly after Merseyrail introduced safety procedures at its Birkenhead North depot to protect maintenance crews while working on the heating units.
An RMT official said: “As with everything containing asbestos they are perfectly safe when in service but care needs to be taken when units are being stripped down during maintenance.”
Breathing in asbestos fibres can lead to lung cancer but white asbestos is not considered to be as dangerous as the banned blue and brown varieties.