Occupied Building Risk Assessment (OBRA)

An Occupied Building Risk Assessment (OBRA) assesses the hazards for building occupants in the event of a major accident. Both location and design of buildings can affect the survivability of people within them. An OBRA assess the risk to building occupants and identifies where additional protection should be introduced, to demonstrate that the risks are as low as reasonably practicable (ALARP).

It requires judgment. There is no simple formula for computing what is ALARP.

It can get very complicated. More detailed ALARP suite of guidance explains how to deal with some of these complications.

The definition set out by the Court of Appeal (in its judgment in Edwards v. National Coal Board, [1949] 1 All ER 743) is:

“‘Reasonably practicable’ is a narrower term than ‘physically possible’ … a computation must be made by the owner in which the quantum of risk is placed on one scale and the sacrifice involved in the measures necessary for averting the risk (whether in money, time or trouble) is placed in the other, and that, if it be shown that there is a gross disproportion between them – the risk being insignificant in relation to the sacrifice – the defendants discharge the onus on them.”

(Contains public sector information published by the Health and Safety Executive and licensed under the Open Government Licence).

You may come across it as SFAIRP (“so far as is reasonably practicable”) or ALARP (“as low as reasonably practicable”). SFAIRP is the term most often used in the Health and Safety at Work etc Act and in Regulations. ALARP is the term used by risk specialists, and duty-holders are more likely to know it. We use ALARP in this guidance. In HSE’s view, the two terms are interchangeable except if you are drafting formal legal documents when you must use the correct legal phrase.

The definition set out by the Court of Appeal (in its judgment in Edwards v. National Coal Board, [1949] 1 All ER 743) is:

“‘Reasonably practicable’ is a narrower term than ‘physically possible’ … a computation must be made by the owner in which the quantum of risk is placed on one scale and the sacrifice involved in the measures necessary for averting the risk (whether in money, time or trouble) is placed in the other, and that, if it be shown that there is a gross disproportion between them – the risk being insignificant in relation to the sacrifice – the defendants discharge the onus on them.”

In essence, making sure a risk has been reduced ALARP is about weighing the risk against the sacrifice needed to further reduce it. The decision is weighted in favour of health and safety because the presumption is that the duty-holder should implement the risk reduction measure. To avoid having to make this sacrifice, the duty-holder must be able to show that it would be grossly disproportionate to the benefits of risk reduction that would be achieved. Thus, the process is not one of balancing the costs and benefits of measures but, rather, of adopting measures except where they are ruled out because they involve grossly disproportionate sacrifices. Extreme examples might be:

To spend £1m to prevent five staff suffering bruised knees is obviously grossly disproportionate; but
To spend £1m to prevent a major explosion capable of killing 150 people is obviously proportionate.
Of course, in reality many decisions about risk and the controls that achieve ALARP are not so obvious. Factors come into play such as ongoing costs set against remote chances of one-off events, or daily expense and supervision time required to ensure that, for example, employees wear ear defenders set against a chance of developing hearing loss at some time in the future. It requires judgment. There is no simple formula for computing what is ALARP.

It can get very complicated. More detailed ALARP suite of guidance and your Directorate/Divisional ALARP guidance (where available) explains how to deal with some of these complications.

(Contains public sector information published by the Health and Safety Executive and licensed under the Open Government Licence).