A dynamic risk assessment is the continuous judgement a person makes about a situation that is changing in front of them, as opposed to the written assessment made in advance for work that is predictable. Emergency services, lone workers, engineers arriving at unfamiliar sites and anyone whose next hour cannot be fully described the day before all rely on it. It is a real and respected idea, and it is also the most frequently misused phrase in workplace safety, because it is what people reach for when they have not done the written one.
What it actually is, done properly
A dynamic assessment is a structured habit, not an absence of process: arriving, taking in what has changed since the job was planned, identifying the hazards actually present, deciding whether the planned controls still fit, adjusting or withdrawing, and telling someone. The people who do it well are trained to a routine and rehearse it, and their organisations give them explicit authority to stop. Where it fails is where it is assumed rather than taught, and where the person on site has no authority to walk away from work that is not safe.
It supplements the written assessment, it does not replace it
The regulations require a suitable and sufficient assessment of the risks, and for foreseeable work that means one made in advance and recorded. A dynamic assessment covers the gap between what was foreseeable and what is actually in front of the person, which is a real gap and a narrow one. If your written assessments are thin and your answer is that the team assesses dynamically, you have not described a method, you have described the absence of one.
The part that is almost always missing is the record
A dynamic assessment that changes what happens on site and leaves no trace teaches the organisation nothing. The pattern that works is small: what was different, what was decided, who was told, and whether the written assessment now needs changing. That last question is the loop, and the free risk assessment form worksheet on this site counts exactly that traffic, because assessments forced out of cycle by a change are usually the largest hidden cost in the programme.
Where it belongs in a set of assessments
Treat it as a named method inside the written assessment for the activities where the situation genuinely varies, with the trigger, the authority to stop and the reporting route written down. That way it is auditable: someone can ask how the method works, who is trained in it and what it produced last quarter, and there are answers. Left as a phrase, it is the thing an inspector asks about after something has gone wrong.
Questions people ask about dynamic risk assessment
What does dynamic risk assessment mean?
The continuous assessment a competent person makes of a changing situation as they work in it, adjusting the controls or stopping the work in response to what they find. It is a method for the unpredictable part of a job, and it assumes training, authority to stop, and a route to report what was found.
Is a dynamic risk assessment a legal alternative to a written one?
No. The duty to make a suitable and sufficient assessment of foreseeable risks, and to record the significant findings where you employ five or more people, is not discharged by assessing on the day. Dynamic assessment covers what could not reasonably have been foreseen, which is a much smaller set than it is usually used to describe.
How do you record a dynamic risk assessment?
Briefly, and against the job. What was different from the plan, what was decided, who was informed, and whether the written assessment needs revising. Anything longer will not be filled in on site; anything shorter cannot be learned from.