The number of extended A & E waits across the UK has more than doubled in the last four years while Hospitals struggle to cope with the demand, according to the BBC analysis.  Northern Ireland has the worst performance, although England has experienced the fastest deterioration, according to figures.
More than 3 million patients who visited UK A & Es waited more than four hours in the last 12 months, an increase of 120% from 2012-13.  In comparison, the number of visits increased by only 7% to 26.9m.
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Doctors and nurses said the findings showed that the NHS could no longer cope with what was being requested and patients were at risk.
And Dr. Taj Hassan, president of the Royal College of Emergency Medicine, said that the A & E system had been "stretched to its limits".
"The staff is working very hard, but we have reached the point where we can not meet the demand.
" Priority is given to life-threatening cases. But a crowded emergency department adds risks. We received delays in the evaluation, pain relief and antibiotics. "
The Royal College of Nursing general secretary, Janet Davies, agreed and described the situation as" intolerable "and the A & E units were" on the verge of explode. "
the units have been telling us that it is difficult for them to do anything other than a gun battle," he added.
How short is the NHS from the target?
The data compiled by the BBC show a significant difference in performance against all four – our goal to treat or admit patients.
In Northern Ireland, which has seen the largest increase in people going to the A and E units, only 75% of patients came in four hours in 2016-17, while Scotland saw 93.9 %. only marginally lower than the 95% target.
In fact, Scotland is the only part of the United Kingdom with better performance than it was four years ago.
England has experienced the largest increase in long waiters, an increase of 155%. Scotland, the number of long waiters actually decreased by 9%.
Regiona In England, West Midlands has the worst performance followed by the Northwest: patients visiting A & Es in those areas are more than twice as likely to wait more than four hours as those in the Northeast, the region with the better performance.
There are minor variations in the way in which the objective is measured in the four nations, although they are considered broadly comparable.
& # 39; Feel you're failing patients & # 39;
The BBC has talked to several employees of the hospital this week about their experiences. Many wanted to remain anonymous given the political sensitivity about the performance of the health service.
But everyone agreed that the pressures were as great as they had ever experienced. A nurse, who works at an A & E unit in South Wales, said her department faced relentless pressure "24/7".
"I know of colleagues who leave a shift and come back the next day and find out that the patient is still there We have seen them in A & E but there are no beds in the hospital, causing overcrowding and all kinds of delays."
" Ambulances queue outside of A & Es as staff are too busy to get patients out of them. I have worked at A & Es for more than 10 years and this is as bad as I can remember. "
Another nurse, from London, said:" You feel like you are failing patients. This is not the kind of care we want to provide, or patients deserve it.
"Obviously, we prioritize the most serious cases, but when it is so busy there is always a risk that something will be lost, sometimes I finish my shift and finish worrying about my patients."
Is there a solution?
Unless the NHS can obtain its existing hospital network to serve patients more quickly, the health service would need another 20 A & Es to reach the goal again.  But each country believes that the answer to the problem lies in trying to control the numbers that appear in A & E and making sure they go through the hospital more quickly when they need treatment by releasing beds.
This is done by ensuring that there are Spare beds in nursing homes and community care services, to deliver fragile patients a.
In Scotland, for example, NHS budgets have been pooled with council funds to create a closer working relationship between hospitals and community care, which It is one of the reasons why ministers believe they have performed better than the rest of the United Kingdom.
In England, an extra £ 1bn in social assistance is being invested this year, while £ 435m has been released to help with winter planning, including putting doctors at A & Es to deal with the smaller cases.
A spokesman for the Department of Health said that the ministers recognize that the NHS was "under pressure due to the aging population", but noted that despite the deterioration, nine out of 10 patients were still being treated in four hours.
Chris Hopson, executive director of NHS Providers, which represents the hospitals, said the money had come too late.
"We are not where we would like to be when we are approaching winter, we can not say with certainty how difficult this will be, but the likelihood is that the services will be harshly tested."
A spokesman for the Government of Wales said that there were signs that performance was improving when you compared this year with last year instead of four years ago.
But he admitted that winter would be "challenging".
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