It took an ambulance at least 90 minutes to arrive at a life-threatening emergency call 20 times in the first six months of the year.
Freedom of Information figures released to Newstalk show the longest waiting time was nearly two hours and 19 minutes.
The target is for an ambulance to arrive at a life-threatening emergency call within 19 minutes.
Between January and June of this year however, the response time was over an hour in 308 cases.
The worst was two hours and 19 minutes to a call in a rural area of County Galway.
That was followed by two hours and 13 minutes to an emergency in County Mayo.
Waiting times of over 90 minutes were also recorded in counties Cork, Wexford, Kildare, Wicklow, Tipperary and Cavan.
Paramedic and Wexford Councillor Ger Carthy said there are several factors behind the problem.
“Geographically, the way the country is laid out, it is mostly rural and it is difficult to adhere to the HIQA response times,” he said.
“But that is the culmination of a massive call volume – the National Ambulance Service (NAS) responds to 365,000 calls a year – and even with the COVID now, that has become more difficult in the context of the decontamination that must happen after each call.”
He said there is a big staffing problem in the service.
“There has been a lot of staff leaving the NSA over the last number of years into the wider HSE, but we have also had a global pandemic and it has certainly had a major impact on the staff of the NSE along the lines of burnout and fatigue and there are probably easier positions within the wider HSE.”
The NAS said the recruitment of staff is being outpaced by the demand for its services, which has grown by almost 30% this year.