What the method calculates
INSST’s Occupational Safety manual describes the method and expresses the degree of danger as the product of consequences, exposure and probability.
The factors are conventional values assigned to categories. The result ranks situations analysed using comparable criteria. It must not become a prediction of how many accidents will occur or be interpreted as a safety percentage.
Distinguish the three factors
Consequences describe harm in the scenario considered. Exposure reflects how often the risk situation occurs. Probability assesses whether, once that situation occurs, the sequence producing the accident and its consequences will be completed.
NTP 934 also distinguishes these parameters in simplified methodologies. Separating them avoids scoring frequency twice. It also requires a specific scenario: a description such as machinery risk is too broad to justify a useful rating.
Define criteria and evidence
Identify the version and tables used without mixing scales from different documents. Scores need support from observations, equipment conditions, tasks, incidents and information from people who understand the work.
INSST identifies difficulty assigning probability without sufficient experience or data as a limitation. Significant uncertainty must be documented and resolved through appropriate analysis rather than hidden behind a precise number.
Difference from NTP 330
NTP 330 also establishes priorities through indices, but starts with deficiency and exposure levels to estimate probability and then combines this with consequences.
The two are therefore not interchangeable templates. A Fine value must not be entered into NTP 330 ranges. Comparing sites or periods requires sufficiently consistent criteria, scope and assessment conditions.
When another analysis is needed
Article 5 of Spain’s Prevention Services Regulations requires a procedure to provide confidence in its result. Where specific legislation requires measurements, analyses or criteria, these must be applied.
A Fine score does not replace an occupational hygiene exposure assessment, ergonomic study or psychosocial assessment. Nor does it demonstrate the sufficiency of a complex technical barrier. Method selection depends on the risk and the decision required.
From priority to prevention
The result must be accompanied by measures, owners, resources and follow-up. Articles 15 and 16 of the LPRL place elimination and control of risk ahead of classification alone.
A protective obligation does not disappear because another situation scores higher. After intervention, check the measure under real conditions and review the assessment where appropriate. Lowering a number without changing the work is not a preventive improvement.
Hypothetical example: two maintenance tasks
A team compares two clearly defined tasks using the same Fine table. For one, the actual frequency of access to a danger zone is unknown, so information is collected before finalising the rating.
The resulting priority helps organise action, but identified breaches are corrected according to their requirements. After measures are installed, their operation is verified and the assessment updated with evidence.
