The Irish Nurses and Midwives Organisation (INMO) says at no time is there the optimum nurse to patient ratio on any ward in any Irish hospital.
It comes following the publication of an international study which shows that every patient added to the nurse to patient ratio increases the number of deaths after surgery by seven per cent.
The INMO says the optimum ratio is one nurse for every four patients but most wards in Ireland operate on a 1-to-7 ratio during the day, and a 1-to-13 ratio at night.
General-Secretary Liam Doran told The Pat Kenny Show here on Newstalk that the government and the Health Service Executive (HSE) have to take action.
The new Europe-wide study says reducing nurse staffing numbers has a major impact on patient outcomes. The figures show that there is a 7% rise in deaths for every patient added to the patient-to-nurse ratio.
A team from Dublin City University (DCU) contributed to the research, which is published today in The Lancet medical journal.
The study of almost 500,000 patients across nine EU countries - including Ireland - found that every patient added to the patient-to-nurse ratio leads to a 7% increase in deaths after surgery. Meanwhilefor every 10% jump in nurses with bachelors degrees there is a 7% drop in deaths.
DCU Professor Anne Scott led the Irish part of the study. She says the results suggest that assuming you can cut nurse numbers to save money without affecting patient care is "misguided at best - and fatal at worst".
Professor Scott told Newstalk Breakfast that patients are at 30% less risk of dying if they are cared for in hospitals where 60% of nurses are educated to degree level, and nurse six patients, as opposed to hospitals where only 30% of nurses have degrees, and they are required to care for more patients.
Over 4,200 nurses have left the Health Service since 2009.
The Irish Nurses and Midwives Organisation says it is publish its own survey in the coming weeks which shows that no Irish hospital wards have nurses looking after fewer than six patients and that number doubles on night duty.
