Firefighters are at much higher risk of developing cancer than the general public and are more likely to develop the disease earlier in life.
The long-term effects of chemicals present when fires burn can cause cancer as well as cardiovascular and neurological diseases, and are known as chronic toxicity.
The shocking statistics were explained to members of Northumberland County Council's Communities and Place Overview and Scrutiny Committee by bosses at Northumberland Fire and Rescue Service, who also explained the steps the fire service is now taking to protect crew members.
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Speaking at the meeting, assistant chief fire officer Jim McNeil said: "Our firefighters are seven times more likely to have cancer than the general public and the probability of that happening comes 22-23 years earlier in their lifespan.
"That is huge, and that is a figure burnt into the brain of firefighters up and down the county."
The fire service has implemented a number of new guidelines around personal protective equipment (PPE) as a result of the issue. These include transporting contaminated PPE in air-tight containers, not eating or drinking with unwashed hands and wearing clean clothes before re-entering a fire appliance after an incident.
Firefighters should also shower within an hour of returning to the station following an incident, while regular health screening is also "strongly advised". Mr McNeil paid tribute to area manager Rob Clow, who is responsible for fire support services and has been leading on the drive to reduce contamination.
He added: "I hope that has given you some reassurance. The work we're doing is probably ground-breaking. We're moving at such a pace that it is almost unimaginable.
"It is absolutely mind-blowing the work that has been put in by Rob and his team. I would like to put on record my personal thanks."
Coun Anne Dale said: "This really shows the dangers you face. It is not just the fires - it's the toxins.
"It is sad to hear people get things from the toxins. We have to do everything to ensure that our firefighters are safe."
The committee agreed to recommend to the council's cabinet that the fire service received "proper funding" to implement further changes to ensure the safety of firefighters.
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