Crumbling local hospital buildings are leaving patients fearing collapsing roofs and rat infestations.
Almost one in five people say their local hospital building is not a safe place to receive care, while 30 per cent do not know if it is safe, according to a poll.
It comes as analysis suggests the repair bill at 18 crumbling hospitals could be set to reach £5.7 billion due to the delay in replacing them.
But a target to deliver more than two million additional elective care appointments has been hit seven months early.
The Government hopes this will bring it closer to hitting a target by the end of this Parliament for patients to get non-urgent, consultant-led treatment within 18 weeks of a referral.
The fears over hospital infrastructure were revealed in a survey of more than 2,000 patients commissioned by the Liberal Democrats.
Among those who thought that their local hospital building was unsafe, 27 per cent thought it was because the roof may collapse, and 26 per cent feared rodents and insects may infest the building.
Around a third of people were afraid the power would go off, and one in five thought there may be a sewage leak or flooding.
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The Liberal Democrats have called for a 'crumbling hospitals taskforce' and the party's health and social care spokesman, Helen Morgan, said: 'Patients should only worry about their health-not whether the roof will cave in on them.
'The previous Conservative government's neglect of the NHS brought us to this disgraceful point.
'Yet, the Labour Government has failed to act fast enough to protect patients from these decaying buildings.'
The previous Conservative government pledged to provide 40 more hospitals by 2030 but Labour last month said this was built on 'false hope' and it will now take at least a decade longer than planned.
Construction of the hospitals is set to proceed in four waves, with the final part not beginning until between 2035 and 2039.
The timetable could see the cost of tackling a backlog of repairs at hospitals hit £5.7 billion, according to calculations from the Liberal Democrats.
This maintenance backlog has increased on average by 10.45 per cent per year since 2019, when the new-build hospitals were announced.
If it keeps rising at the same rate, it will hit £5.7 billion by the time construction is due to begin in the 2030s, the Lib Dem analysis found.
The pledge to deliver more than two million more elective care appointments means thousands of patients have received operations, scans, treatments, and consultations earlier than planned.
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But not every appointment delivered will reduce the number of patients on the huge NHS waiting list, as people can require multiple appointments before receiving a diagnosis and then starting treatment.
The waiting list now stands at an estimated 7.46 million treatments, with figures published last week showing the waiting list has been cut by almost 160,000 since Labour took office.
However new figures published by NHS England reveal that between July and November last year, the NHS delivered almost 2.2 million more elective care appointments compared to the same period the previous year.
The extra appointments, delivered in part by extra evening and weekend working, included chemotherapy, radiotherapy, endoscopy and diagnostic tests.
Some 62 per cent of the additional activity was made up of outpatient appointments, 26 per cent of diagnostic tests and 12 per cent of elective operations.
The Government is set to hand an additional £40 million to NHS trusts that deliver the biggest improvements in cutting waiting lists.
Sir Keir Starmer said: 'We said we'd turn this around and that's exactly what we're doing – this milestone is a shot in the arm for our plan to get the NHS back on its feet and cut waiting times.
'But we're not complacent and we know the job isn't done.
'We're determined to go further and faster to deliver more appointments, faster treatment, and a National Health Service that the British public deserve as part of our Plan for Change.'
NHS chief executive Amanda Pritchard said: 'Thanks to the hard work of staff and embracing the latest innovations in care, we treated hundreds of thousands more patients last year and delivered a record number of tests and checks, with the waiting list falling for the fourth month in a row.
'There is much more to do to slash waiting times for patients, but the Elective Care Reform Plan will allow us to build on this incredible progress as we boost capacity and drive efficiency while also improving the experience of patients.'
Health Secretary Wes Streeting said: 'We have wasted no time in getting to work to cut NHS waiting times and end the agony of millions of patients suffering uncertainty and pain.
'Because we ended the strikes, invested in the NHS, and rolled out reformed ways of working, we are finally putting the NHS on the road to recovery.'
A spokesman for the Department of Health and Social Care said: 'The NHS estate we inherited is crumbling but repairing and rebuilding our hospitals is a key part of our ambition to create a health service fit for the future.
'The New Hospital Programme is now on a credible and sustainable footing, and we are committed to delivering all schemes, and we are also investing over £1 billion to address the backlog of critical NHS maintenance and repairs and tackle dangerous RAAC concrete, to help ensure hospitals are safe and sustainable.'