A health economist says targets to cut HSE waiting lists could be hampered by the 'challenging' recruitment of staff.
Brian Turner was speaking as a €350m plan to reduce hospital waiting lists will be published later this week.
Currently, more than 17,500 people have been waiting for an inpatient procedure for more than 12 months.
While 155,000 people have been on the outpatient waiting list for more than 18 months.
No patient will have to wait more than a year for an inpatient procedure, or 18 months for an outpatient appointment, by the end of this year under the new plans.
Dr Turner, health economist at UCC, told The Hard Shoulder it is good to see ambition.
"I think it's good that they are having this target, at least they're working towards something.
"But it is going to be a very big challenge.
"At least they have the ambition to do it, and it is part of a broader plan to try and bring waiting times down."
He says procedures will have to increase on a daily basis to reach such targets.
"They're hoping to have an additional 210,000 in-patient or day care procedures compared with last year.
"That's a significant increase, you're talking about over 10% of an increase on what was carried out last year."
But Dr Turner says capacity issues have not gone away.
"Part of the issue is the capacity constraints, which are a long-standing issue in the Irish health system.
"The health budget for last year included an extra €4bn just to try and bring up the capacity.
"But that hasn't all come through, because obviously the physical capacity... takes a long time to build and to operate.
"The workforce capacity as well is proving a bit more challenging than the HSE had hoped in terms of recruiting additional staff.
"In that context, we are competing in a very competitive, international market for a healthcare workforce".
He says a forecast suggests there will be shortage of 386,000 doctors and 2.5 million nurses across OCED countries by 2030.
Dr Turner says an increase in funding to the National Treatment Purchase Fund - to try and get people treated privately - could be another way.
"Investment in that could have the benefit of increasing the capacity in the step-down facilities, but also increasing the capacity in hospitals at the same time".
He adds: "It is good to have these targets and I suppose now that these targets are out there, they can be measured against those targets.
"We can see, at the end of the year, have they actually achieved what they said they were going to achieve.
"So at least it is now a measurable target that's out there, that we can actually look at the end of year and judge them upon it".