How many hospital black alerts were there this week?

That's according to media reports, which say that 23 hospital trusts in England have reached the highest level on the NHS’s system for saying whether they are under pressure, or are otherwise under serious strain. The Department of Health doesn't use the term 'black alert'.

“20 hospitals yesterday declared a black alert, so that’s the worst thing you can declare”. Paul Mason, 12 January 2017

It was reported by the Guardian on Wednesday 11 January that 23 hospitals had declared ‘black alerts’ since the previous Monday.

This mostly refers to hospital trusts reporting a high level on NHS England’s Operational Pressures Escalation Levels (OPEL). This is a series of levels that hospital trusts can say they are at to indicate how much pressure they are under.

OPEL 1 is the least severe and is used when hospitals can “maintain patient flow and are able to meet anticipated demand within available resources… Additional support is not anticipated”.

At the other end of the scale, OPEL 4 is when “organisations [are] unable to deliver comprehensive care” and “there is increased potential for patient care and safety to be compromised”. OPEL 4 also means that external support for the trust is required.

The guidelines also say that “Where multiple systems in different parts of the country are declaring OPEL 4 for sustained periods of time and there is an impact across local and regional boundaries, national action may be considered.”

The Guardian reported that most of the 23 trusts it described as being on ‘black alert’ had actually gone onto OPEL 4. The Department of Health told us that it doesn’t use this phrase.

We’ve asked NHS England whether or not the Guardian’s figure is accurate. The latest published figures are for 7 and 8 January.

On these two days there were no OPEL 4s, but 52 trusts had reported an OPEL 3. This means that the trust was “experiencing major pressures compromising patient flow” and that some outside help might be needed.

Since 31 December there have been 74 hospital trusts which said they were at OPEL 3 or 4 on one or more days. That’s just under half of all trusts in England. Eight of these said they were at OPEL 4.

This fact check is part of a roundup of BBC Question Time, factchecked. Read the roundup.