The Welsh Conservatives say this is the crisis at the heart of A&E departments.
According to a Freedom of Information Request by the Leader of the Welsh Conservatives, Andrew RT Davies, health boards are falling well short of the recommended 'baseline' for staffing levels in emergency departments.
The Royal College of Emergency Medicine sets a 'baseline' for the number of WTE consultants which should be employed in each department to guarantee safe cover - at present no health board is meeting this baseline in Wales, placing patients in potential danger.
The figures below are the most recently available - as of first week of December 2015.
Abertawe Bro Morgannwg: 82.5%
Aneurin Bevan: 68%
Betsi Cadwaladr: 41.3%
Cardiff & Vale UHB: 51.8%
Cwm Taf: 37%
Hywel Dda: 15%
Powys: Not applicable [No major hospitals]
Across Wales only one hospital [Morriston Hospital, Swansea] is meeting the Baseline - at 110% of the required staffing. Wales' largest hospital [University Hospital of Wales, Cardiff] has just 51.8%. Others are worse:
Prince Philip Hospital: 10% [Hywel Dda]
Bronglais Hospital: 10% [Hywel Dda]
Ysbyty Glan Cwyd: 20% [Betsi - North Wales]
Welsh Conservatives say the figures "highlight the staffing crisis at the heart of the Welsh NHS",
Leader of the Welsh Conservatives, Andrew RT Davies, said, "It's clear from these figures that Welsh A&E units remain dangerously short-staffed, and the knock-on effect is that Welsh patients are facing dangerously long waits to be seen in an emergency.
"It's just not good enough, and places huge pressure on hardworking NHS staff.
Earlier this year Wales' most senior A&E doctor described Welsh A&E departments as "on the edge" and in some parts of Wales staffing levels appear to have got worse in recent months.
"Several health boards are now operating at less than half the required base level for emergency cover. That's the legacy of Labour's record-breaking health cuts."
Shadow Health Minister, Darren Millar, said, "These figures highlight the staffing crisis at the heart of the Welsh NHS.
"Welsh Labour's performance against their own NHS targets is totally unacceptable, and the state of the Welsh NHS shows that they're simply not up to the job.
"Across Wales just one hospital is meeting the baseline of required staffing, and the results are hardly surprising.
"Last month around 3,300 patients waited more than 12 hours to be seen in a Welsh A&E unit - compared to just 158 across the whole of England.
"It's clear that Labour have let Wales down, and only the Welsh Conservatives can be trusted to protect the Welsh NHS by guaranteeing more investment in our health service each and every year."