The Irish Nurses and Midwives Organisation (INMO) has begun a ballot of its members in the Emergency Department of University Hospital Galway in a dispute over staffing levels.
The union said workers are dealing with untenable workloads and unsafe conditions.
The INMO has accused the HSE of failing to take seriously the staffing deficits in the Emergency Department and the impact on the ability of nurses to provide a safe service to patients.
The union said that a combination of unfilled positions, a failure to retain existing staff, and short-term or lacklustre recruitment campaigns, have left the department in a dangerous situation.
"Patients are now waiting up to three hours to be triaged, and the department is suffering from a lack of round-the clock clinical oversight, leading to risks to patients and intolerable pressure for staff," said INMO Assistant Director of Industrial Relations Mary Fogarty.
"Now, as our members have been warning, increased winter attendances to the ED, and the surge in demand caused by winter viruses, mean the situation has become untenable for both staff and patients."
"Unfortunately, although this matter has been brought to management numerous times over the past five months, a lack of action has led our members to the point where they are forced to consider industrial action," Ms Fogarty added.
The HSE has been contacted for comment.
