# 14.1 Identifying risk

It might be surprising to learn that there are many varied definitions of risk. A common interpretation is that risk is the likelihood (or probability) that harm will actually be done by the realisation of the hazard. A hazard is the inherent potential for something to cause harm to humans or their environment. A short-hand way of writing this is:

Risk = Hazard × Exposure

Risk is thus the probability or likelihood of being exposed to a hazard. For humans, radiation is a hazard, carbon monoxide is a hazard, mercury pollution in rivers or air is a hazard. Table 5 identifies how these might be registered in general terms.

## Table 5 Example of a risks and hazards register

Risk | Hazard | Exposure
--- | --- | ---
Poisoning | Carbon monoxide | Car journeys, domestic fire/boiler
Poisoning | Radiation (various types) | Mobile phones, aircraft journeys
Poisoning (humans, soils, water, species) | Mercury | Breakage of energy saving light bulbs, improper dumping of computing equipment, gold mining

A more detailed risk assessment and analysis would develop Table 5 with qualitative and quantitative scores to indicate the level of risk, scale of the hazard and possibility of exposure. However, it is not easy to quantify the probability of risks occurring because of the complexity of many situations, never mind the difficulties of communicating probabilities mathematically (as outlined in this BBC News Magazine article).

Just as with systems being ‘observer dependent’, risks are not understood by all or interpreted equally. Risk awareness varies because of different interpretations of hazard and the probability of the hazard occurring. Jumping off a high diving board at a swimming pool may be fun and ‘not risky’ for person A, but person B might be terrified at the thought of so doing. Their perceptions of the risk (the probability of the hazard occurring) are very different.

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