The Irish Nurses and Midwives Organisation say five hospitals experienced their worst-ever overcrowding this September.
The union record the numbers of patients on trolleys every day, and say the University Hospital and the Mercy University Hospital in Cork, as well as Portiuncula, Letterkenny and University Hospital Kerry all, saw higher numbers of people waiting for a bed than any other year.
A spokesperson for the INMO says overcrowding figures reached record lows in 2019 and 2020 due to the pandemic, but is warning that hospitals are "returning to the bad old days".
In University Hospital Galway, there were nearly forty times as many this month compared to 12 months ago. (805 vs 21).
The figures come as four nurses in University Hospital Galway have quit, due to conditions in the hospital’s temporary emergency department.