The Irish Nurses and Midwives Organisation (INMO) has asked for an emergency meeting with the Health Service Executive (HSE) to discuss the unacceptable level of overcrowding in hospitals.
The INMO wrote to the health service on Friday, outlining their concerns with overcrowding is in accident and emergency departments.
The nurses' union said members are working in "hazardous conditions" and they do not have the reserves to cope with the level of pressure facing them.
Karen McGowan, INMO president and emergency department nurse, said it is time for the HSE to start addressing the issue of "staff burnout" and not let their working conditions get worse.
"It is not acceptable for the HSE to rely on the goodwill and professionalism of nurses rather than develop a viable plan for safe staffing," she said.
Ms McGowan added that if conditions do not improve "it will be very difficult to retain nurses and midwives" over the coming years.
Around 2,800 patients have been treated on trolleys so far this month, which is almost double the number in the same period last year, while more than 22,000 patients have received similar care since the beginning of 2021.
Trolley figures for May of this year (3,898) were more than triple the amount when compared with figures from the same month in 2020.
Tony Fitzpatrick, director of industrial relations at the INMO, says overcrowding in emergency departments is not acceptable.
"All we've seen is an increase in attendances, increases in admissions and therefore there's a need for an engagement with the HSE about how we're going to deal with the crowding situation," he said.
"When we have Covid-19 in the community, and now we have new variants, it's vitally important that we don't allow our emergency departments to become crowded again."
On the issue of the coronavirus, INMO general secretary Phil Ní Sheaghdha said the risk of Covid transmission in hospitals has not gone away, and that this is not the time to be "reckless" with overcrowding and patient safety.
“We are looking at highly transmissible variants, combined with a completely exhausted workforce," she said.
"What we need from Government and the HSE is a concrete plan to deal with this situation before it becomes even more dangerous.”
Meanwhile, Tánaiste Leo Varadkar will tell the Fine Gael ard fheis this evening that the €4bn in additional spending given to the health service to fight the Covid-19 pandemic “should be retained” permanently.
Thehas confirmed that, in his keynote address, Mr Varadkar will state that the increased staffing levels, resources, and now €22bn-a-year budget provided to the health service to respond to the crisis should not be cut back as is due to happen to other Covid spending.
“I believe the additional staff, resources, and billions in extra funding that we have provided to the health service to respond to the emergency should be retained and redeployed," he will say.
However, Sinn Féin's spokesperson for health criticised the Tánaiste's "hypocrisy" on health commitments from his party's time in Government.
David Cullinane said: "Waiting lists have more than doubled during Fine Gael's period in Government, with estimates putting the total number over one million."
The Waterford TD added that while a promise of increased funding is welcomed, it needs to be followed through with "targeted action to fix the severe problems".
"Measures from the last budget have yet to be implemented, and the health service is suffering from chronic underinvestment in capacity, equipment and modern IT systems," Mr Cullinane said.
"The Tánaiste's reaction to the crisis is a recognition that his and Fine Gael's policies over the last 10 years have failed."