The HSE has said a "robust contingency plan" is being implemented around the country, as 500 ambulance personnel are on strike in a row over union recognition.
Senior management within the National Ambulance Service (NAS) are continuing to monitor the situation.
"Their focus is the delivery of a safe service for the public and while the volume of calls to date is as anticipated, the ability to respond has been maintained to date", the HSE said.
It said in an emergency situation, the public should call 112/999 as normal and the National Ambulance Service will respond.
Members of the Psychiatric Nurses Association (PNA) are picketing at bases in Dublin, Cork and other locations until 5.00pm this evening.
Ambulance personnel who belong to the PNA want the HSE to recognise the trade union, as well as deduct and remit their subscription fee from their pay.
500 ambulance personnel are striking at bases across the country today in a row over union recognition.
I’ll be on @BreakfastNT at 8:15 from the picket line pic.twitter.com/s2gm33IpHh
— Kacey O'Riordan (@KaceyORiordan) January 22, 2019
The HSE, meanwhile, says it already recognises SIPTU, UNITE and FORSA - and believes engaging with any further organisations would harm good industrial relations in the NAS.
In a statement, the HSE argued: "Where grades of employee already have strong representation rights – as is the case in the National Ambulance Service – it is not appropriate for employers to recognise break-away unions.
"National Ambulance Service will stand by the agreements that it has made with recognised unions and will not undermine those agreements by engaging with other associations or unions."
The Department of Defence has a number of ambulances on standby, while managers who are qualified paramedics will be carrying out front-line duties.
SIPTU, which represents the most front-line staff, has confirmed that it expects its members to work as normal.
The PNA, meanwhile, has said it will not call on other unions to join the strike and will provide emergency cover where necessary.
Additional reporting: Jack Quann
