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Measuring health and safety performance is part of the “check” stage of Plan, Do, Check, Act. Indicators fall into two groups: lagging indicators, which measure harm that has already happened, and leading indicators, which measure whether the things that prevent harm are being done.
The difference
| Lagging indicators | Leading indicators | |
|---|---|---|
| What they measure | Outcomes: injuries, ill health, damage | Inputs and activities: inspections, training, controls |
| Also called | Reactive monitoring | Active monitoring |
| Strength | Easy to count and compare | Show problems before someone is hurt |
| Weakness | Too late to prevent harm, and low numbers can hide serious risks | Can become box-ticking if not linked to real risks |
Examples of lagging indicators
- Number of lost time injuries
- RIDDOR reportable injuries and dangerous occurrences
- Cases of work-related ill health
- Days lost to injury and ill health
- Enforcement notices and insurance claims
Examples of leading indicators
- Percentage of planned inspections completed
- Percentage of inspection and audit actions closed on time
- Number of near miss reports and how quickly they are acted on
- Training completed against plan, such as refresher training in date
- Percentage of risk assessments reviewed on schedule
- Statutory examinations, such as LOLER and LEV, completed on time
- Senior leader safety tours carried out
- Toolbox talks delivered and attendance
Accident frequency rate
A common lagging measure in the UK is the accident frequency rate: the number of reportable injuries multiplied by 100,000, divided by the total hours worked. For example, 2 reportable injuries in 400,000 hours gives a rate of 0.5. Using hours worked lets you compare sites and years of different sizes.
Choosing good indicators
- Start from your biggest risks. A construction firm might track temporary works checks; a warehouse might track forklift pre-use checks.
- Pair each leading indicator with the outcome it is meant to prevent.
- Measure quality, not just quantity. Ten poor inspections are worse than five good ones.
- Keep the set small enough for people to act on.
- Review them regularly and change them when they stop being useful.
HSE’s guidance HSG254 describes how to choose paired indicators for major hazards, and the principle works in any business.
Reporting to the board
Directors need a short, balanced view: a few lagging measures, the key leading measures for the main risks, trends over time, and the main actions. Our guide to the Corporate Manslaughter Act explains why board-level oversight matters.
Training that helps
The NEBOSH Health and Safety Leadership Excellence certificate and IOSH Leading Safely help senior leaders ask the right questions about safety data. The NEBOSH National General Certificate covers active and reactive monitoring in detail, and the Level 7 Diploma covers performance measurement at strategic level.
Frequently asked questions
What is a leading indicator in health and safety?
A measure of whether the activities that prevent harm are being carried out, such as inspections completed or training in date.
What is a lagging indicator?
A measure of harm that has already happened, such as lost time injuries.
How do you calculate the accident frequency rate?
Number of reportable injuries multiplied by 100,000, divided by total hours worked.
Is a near miss a leading or lagging indicator?
Near miss reporting is usually treated as a leading indicator, because it shows problems before anyone is hurt.
Read the source
HSE HSG65, Managing for health and safety; HSE HSG254, Developing process safety indicators; HSE and IoD, Leading health and safety at work (INDG417); and ISO 45001:2018, clause 9.1. Facts checked on 6 October 2026.
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