The 'actual' risk of an activity is defined by 'risk factors'. These spell out the likelihood of damage occurring. e.g. the risk factor for working with asbestos is high. 3000 people a year die from previous exposure to asbestos, due to an otherwise rare cancer of the lining of lung called Mesothelioma. Death may occur many years after exposure to very low levels. Many farms still have asbestos present.

There are lots of 'risks' in terms health effects from exposure to chemical, biological, physical hazards. The Health and Safety Executive define risk as the "likelihood of the hazard's potential being realised". A hazard is something with potential to cause harm. Risk refers to potential to cause damage to people. But, "Risk" means different things to different people.

Young people are less likely to be able to see certain risks, as they have not had the chance to experience what happens when things go wrong.

Experience can teach us what to look out for. We can learn what to do or avoid. The trouble is that doing a job for along time can also lead to complacency. Have you ever heard anybody saying: "I've always done it like this and nobody has come to harm"

You may also assess risk differently if you are on the receiving end of the possible risks.