Only two of 10 vehicles forming a key part of any rescue effort after a chemical or biological terror attack in London were available on Sunday night.
Union and management are in dispute over the Incident Response Units
Some firefighters are refusing to drive the vehicles arguing they need at least two crew members on board.
But London Fire Brigade commissioner Ken Knight rejected union claims the dispute was about health and safety.
He told BBC Radio 4's Today programme said the Fire Brigades Union (FBU) had "coerced" its members into the action.
The Incident Response Units (IRUs) central to the dispute are designed to go to the scene of an emergency.
It is thought each has enough equipment to decontaminate 400 people per hour.
Speaking anonymously to Today, one firefighter said: "The danger is that it's a new vehicle to us.
Designed for two?
"We're not used to the size of it so you've to negotiate your way through London in a big vehicle.
"Bearing in mind the way in which you have to attend the incident you want all the help you can get to get it there.
"You don't really want to pull over ... and ask for a police escort."
Another firefighter, who also wished not to be named, said the radio equipment in the IRUs was designed to be used from the passenger seat.
But Mr Knight said it was "scary" that the FBU had instructed members not to use "this very valuable equipment ... in the event of a terrorism attack".
Breaking the link
He said that an independent report a week ago showed it was safe for "one driver to take the vehicle to the incident where it would be met by eight normal fire engines with some 40 firefighters deployed".
Last week the FBU voted to break its historic 86-year link with Labour over the government's "betrayal" of working people.
Delegates at the annual conference in Southport backed a resolution saying the aims and objectives of the party no longer reflected those of the FBU.
The move will deprive the party of £50,000 a year.