Limerick City Ambulance Service began an unofficial picket at 8 a.m. in protest at working conditions.
The picket will continue until midnight and a limited emergency service is being provided. The Mid-Western Health Board says no notice of the protest was given.
SIPTU, which represents the ambulance workers, said today's action is unofficial and is due to frustration and annoyance at the lack of facilities at the base in Dooradoyle, which is also a training centre for Emergency Mobile Technicians.
SIPTU believes there is goodwill on both sides and this should mean the situation will not escalate. It plans to arrange a meeting with the health board to deal with the issues.
In 1998, with the introduction of two-person ambulance crews, staff numbers increased by 150 per cent, and, according to SIPTU, facilities were no longer sufficient for staff numbers.
Currently there are 35 staff, including 10 women. There is only one shower, one toilet and one changing room between the staff.
A spokesperson for the Mid-Western Health Board said it did not dispute working conditions were less than ideal. Planning permission for interim refurbishment at an approximate cost of £70,000 was granted last Friday.
Limerick City Ambulance Service is the largest ambulance base in the Mid-Western Health Board region. It covers an average of 30 emergency calls per day, and at busy times five ambulances are on duty.