A union last night insisted patients would not be put at risk by plans to limit the number of 999 calls paramedics respond to in the last hour of their shift.

The East of England Ambulance Service Trust (EEAST) is considering stopping staff from responding to certain emergencies in their final hour of work because it can often lead to the paramedics working two or three hours beyond their shift – causing stress.

Unison, the largest public-sector trade union, is putting pressure on EEAST to make changes after a survey it commissioned found that 65% of staff said late finishes caused them high levels of stress – with 55% considering leaving because of the issue.

EEAST is assessing taking forward elements of a proposal which include paramedics not responding to all serious and non-emergency calls in the last hour of their shift and some life-threatening calls, known as ‘Red 2s’ in the last 30 minutes.

Paramedics would still have to attend ‘Red 1’ calls, the most serious, and all calls for ‘urgent back-up’ during their final hour.

An EEAST spokesman said the trust’s board had dismissed the proposal as a whole but could look to take on “elements” of it in a pilot programme.

A risk assessment produced by EEAST on the initial proposal warned that making the change could have a “catastrophic consequence”, and risk lives.

Tim Roberts, regional organiser for Unison Eastern said too many staff were working “two-three hours” beyond their normal day because they were attending emergencies including ‘Red 1’ and ‘Red 2’ calls in their last hour of their shift.

‘Red 1’ calls are of the highest priority and involve life-threatening incidents such as cardiac arrest and major bleeding. ‘Red 2’ calls include emergencies such as strokes and seizures.

Mr Roberts said the proposal would ideally work by paramedics who started later picking up calls normally answered by a colleague in the final hour of work. He said staff would base themselves at the same location as part of a handover in their final hour. Another idea mooted is for emergency crews to swap over while at the ‘scene’ of an emergency, he added.

He said: “We do not accept that patients’ lives will be put at risk. Red 1 and Red 2 calls will still be responded to by the nearest resource. If they are in the last minute of their shift they have to respond, full stop.

“What we would like to see is the trust look at all possible ways to deploy resources to balance patient safety and staff welfare. If we continue to lose paramedics at our current rate then there will not be enough ambulances on the road, it will be a significant problem.”

The EEAST spokesman said no proposal “had been agreed” and the implications were being analysed.

“The issue of late finishes was recently identified as a major cause of stress for staff, and was discussed at length during a board meeting with Unison where it was agreed urgent action was needed,” she said.

“The scope of the pilot has yet to be decided upon, so nothing has been finalised – patient safety, clinical excellence and staff support is of the upmost importance and will be high on list of considerations before any decisions on the next steps are determined.”

EEAST is responsible for more than six million people and covers Suffolk, Norfolk, Essex, Cambridgeshire, Hertfordshire, Bedfordshire.