The crucial difference is that for Health and Safety, you risk assess possible damage to people at work. With environmental risk assessment, you assess the possible impacts to all the environment - land, air, water AND people, both inside and outside your workplace.

Risk is the product of the estimated degree of harm (death or damage) of a given impact and its possibilities and magnitude of it happening.

Put another way: The basic calculation used in a risk assessment is to multiply the severity or significance of the impact with the likelihood of it occurring.

So there are two components to risk - possible severity and likelihood.

Let's look at these two parts and how we use them to make an environment risk assessment.