Figures from the Irish Midwives and Nurses and Organisation show there were over 600 people waiting for a bed in hospitals across the country on Thursday morning.
Some 611 patients were being treated on trolleys, chairs and in very clinically dangerous and environmentally inappropriate spaces in hospitals.
There were 423 people waiting in emergency rooms, while 188 people were elsewhere in hospitals across the country.
The hospital with the highest number of people on trolleys was University Hospital Limerick, with 82 people waiting for a bed.
Some 31 people were waiting in the emergency department, while 51 people were elsewhere in the hospital.
Cork University Hospital had 80 people on trolleys, with 67 people in the emergency room.
At University Hospital Galway, there were 53 people without a bed, with 38 patients in the emergency department.
Speaking about the figures, INMO general secretary Phil Ní Sheaghdha said: “As we face into a second significant weather warning in the space of two weeks, the number of patients in high-risk areas continues. Nurses and midwives will be making very dangerous journeys into work tonight and tomorrow in to very busy emergency departments and wards.
“Over 10,000 patients have been treated on a trolley so far this month, on course to be the worst January for overcrowding since the INMO began counting trolleys in 2006. Our members tell us that the age profile and acuity of patients being admitted is noticeably higher.
"The situation in many hospitals is completely unworkable for our members who are currently trying to offer care in intolerable circumstances. Nurses and midwives now have additional concerns about their inability to provide safe care due to overcrowded wards.
"Members are angry that the HSE are insisting on placing patients in totally unsuitable clinical environments contrary to the risks identified by nursing staff.
"We are hearing of so many incidents of vulnerable patients being placed on infection control wards, despite high risks identified by nursing staff who have been overridden by non-clinical staff, and this is simply unacceptable to clinical nurses who are obliged to advocate for patients.
“Dramatically reducing the number of patients being treated in inappropriate spaces must be one of the top priorities for the new Minister for Health once they have been appointed later today. Radically scaling up capacity and staffing is the only credible long-term solution to ending the perennial overcrowding crisis”
