Glossary · Risk assessment and risk reduction
Risk
In machine safety, risk is the combination of the probability of occurrence of harm and the severity of that harm. It is always related to a specific hazard and a hazardous situation.
- Machine safety
- Risk assessment
In one sentence
In machine safety, risk combines how likely harm is with how severe it would be, and is estimated separately for each hazard and hazardous situation.
Example
Two hazards on a conveyor may have similar severity, but the risk at the frequently accessed transfer point is higher than at a drive that is only reached during annual maintenance.
How it applies
- Risk estimation: ISO 12100 breaks the probability of harm into exposure of persons, occurrence of the hazardous event and the possibility to avoid or limit harm. Severity is assessed separately.
- Risk assessment: Risk is estimated per hazard and situation, not per machine. A single “low risk” rating for a whole machine hides the hazards that matter.
- Technical documentation: Keep the estimation parameters visible in the risk assessment, so that reviewers can follow and challenge the result.
- AI regulation: The EU AI Act also defines risk as the combination of the probability of harm and its severity, but applies it to harms including fundamental rights. See the risk-based approach.
Risk vs. hazard
A hazard is a potential source of harm. Risk exists only when exposure makes harm possible, and it can be reduced by lowering either probability or severity.