Hertfordshire County Council is moving ahead with its plans to cut the size of fire crews from five to four.
The community safety and waste management cabinet panel voted in favour of the plans at a meeting on Friday, which would need full approval of the county council cabinet before going ahead.
Labour county councillor for Stevenage Joshua Bennett Lovell - who along with fellow party Cllr Joan King were the only two to vote against the plans - questioned the safety of reducing traditional fire crews.
The concern was further echoed by Hertfordshire Fire Brigades Union Secretary Daren Scotchford after the meeting, who called for a further review of the plan.
"The FBU have significant concerns with a number of proposals contained within the draft plan," he said.
The proposal - outlined as part of a package of plans for the future of the Hertfordshire Fire and Rescue Service, known as the IRMP, earlier this year - has prompted fears that the public and firefighters could be put at greater risk.
"We are particularly concerned that, despite widespread public opposition to reducing crew sizes from five firefighters to four on frontline appliances, the IRMP still proposes this reduction," said Mr Scotchford.
"We would urge the county council to think again on this and other proposed cuts, as we believe they will be to the detriment of both firefighters and the public's safety and welfare."
"Our members are prepared to defend their service and all options to achieve this remain on the table."
Reported incidents have been increasing in recent years, with crews going to a total of 1,216 in the Welwyn Hatfield and Potters Bar area, 2,172 in North Herts and 874 in St Albans in 2017-18.
But the revised IRMP argues that having a crew with four firefighters is "appropriate and cost effective".
It says the vast majority of appliances in the county are already crewed with a maximum of four, and suggests that reducing the size of crews may even improve cover in some areas of the county.
It says: "By officially adopting this policy we can take a holistic view of the service and deploy spare capacity across the organisation, including to on call stations.
"This will then provide a better and more even spread of firefighters across the entire county which will significantly improve our day time fire cover in more rural areas."
The IRMP stated that trying to crew an engine with a certain number of firefighters can lead to an inflated response to serious incidents - meaning that if 60 personnel are required to go to a scene at any one time a total of 248 personnel can actually be used for the whole response.
Liberal Democrat county councillor for St Albans John Hale said everybody was concerned that the changes to crewing should go without event or incident, and that they would want to make sure there were appropriate numbers for the safety of the public and for fire officers.
Herts deputy chief fire officer Chris Bigland also asked the panel to trust their professional judgement, which was based on evidence.
The whole panel - made up of Conservative and Lib Dem councillors - ultimately approved the revised IRMP with only the two Labour councillors on the panel voting against.
Since the proposals in the IRMP were first made public in December there has been a public consultation and open meetings.
Most of the 120 who responded to the consultation - 58.6 per cent - said they disagreed or strongly disagreed with the plan to reduce the crew size.
It was also reported to the meeting that just 49 people had attended the three public meetings, held in Watford , Berkhamsted and Hertford.
The relatively low turnout was highlighted by Conservative county councillor for North Herts Simon Bloxham, himself a former firefighter, who suggested people not turning up may be a signal that they were quite happy with the plans in the IRMP.
Meanwhile councillors were asked to back a recommendation to trial a new 'rapid response vehicle' - which would have a crew of three - at Watford Fire Station.
This would be in addition to the two existing Watford fire engines.
All the proposals on the IRMP will need to be backed by the council's cabinet before they can be implemented.
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