Risk Assessment is the evaluation of risk through quantitative or qualitative measures. The risk assessment attempts to answer the three fundamental questions of risk assessment.

1. What can happen?
   
   Industrial accidents (past or potential), historic contamination of the environment or planned industrial activities (e.g., routine emissions or construction activities) that may impact the environment are all examples of events than can happen. For each assessment, the specific nature of these occurrences are examined, detailed and quantified. This stage of the assessment can be taken further to account for movement of stressors (e.g. contaminants) to other locations or uptake by environmental receptors (e.g. plants, animals, people).
   
   
2. How likely is this to happen?
   
   Assessment of likelihood may range from qualitative assessments of degree of likelihood through to detailed quantitative assessments of failure modes and probabilities.
   
   
3. What are the consequences?
   
   The concerns identified as "what can go wrong" are further assessed to determine their potential effects on environmental receptors. Potential consequences included adverse effects on the health of ecological species and humans, physical damage to structures, socio-economic impacts and other consequences.
   
   

The stages of the assessment are combined to identify those occurrences and impacts with the combined highest consequence and highest likelihood. These are the occurrences of greatest concern, warranting the greatest efforts towards risk management. When high uncertainties combine with likelihoods and consequences, further studies or analyses to reduce uncertainties can be targeted very specifically for the greatest reduction in uncertainty per dollar spent.