More than 10,000 ambulance workers in England and Wales will go on strike on Wednesday, with the public being warned patient safety cannot be guaranteed during the walkout.
The strike will also involve 25,000 paramedics, as well as control room staff and support workers.
Workers in ambulance services and some National Health Service (NHS) trusts voted to strike due to a government-imposed 4% pay raise. Employees asked for above-inflation pay raises.
The country's inflation eased to 10.7% in November, from 11.1% in October, the highest since October 1981.
Meanwhile, strikes in Scotland were cut short after the Scottish government returned to the negotiating table, with some unions accepting an offer to raise pay by an average of 7.5% that others are still evaluating.
Speaking to Sky News, Health Secretary Steve Barclay addressed whether he would do similarly, saying: "One of the big misconceptions about the deal in Scotland … it wasn’t simply 7.5%. If you add in all the other measures in terms of reducing hours, extra annual leave, changes to the way overtime is addressed, protected learning time, actually the cost of that is much more significant and, as I say, one of the trade unions has rejected that as well."
Writing in the Daily Telegraph, Barclay also said: "We now know that the NHS contingency plans will not cover all 999 calls. Ambulance unions have made a conscious choice to inflict harm on patients."
Matthew Taylor, chief executive of the NHS Confederation, told BBC Breakfast: "These strikes come on top of the fact that we are already in a very challenging situation.
"In most parts of the country the ambulance service is well away from meeting its targets for responses to those kind of category 2 cases – so not absolutely urgently, life threatening, but still very important urgent and critical cases."
Nearly 750 armed forces staff have been drafted across the country to help during the walkouts, though their role will be restricted. They will mostly be driving ambulances.
Britain is currently experiencing a wave of industrial action, including nurses, postal workers, and university lecturers, sparked by a bitter cost-of-living crisis triggered by soaring inflation and a deteriorating economy.