Many different methods and tools can be used within HIA, risk assessment and cost-benefit analysis are among the most common.
Risk assessment is a systematic approach to quantify the burden of disease/injury resulting from risk factors. Risks are defined as the probability of an adverse event (eg admission to hospital for respiratory problems when pollution levels increase) and/or a factor that raises the probability of an adverse event (living close to a busy road).
Risk assessment information can be used in the appraisal stage of HIA, to help understand the potential relationship between the proposal and the determinants of health. Risk assessment can be used for those risk factors where there is good quantitative evidence of a dose-response relationship and clear exposure. It can also be used for priority setting among the risks identified.
Some organizations and individuals use the term "comparative risk assessment" interchangeably with health impact assessment. This is why several published "HIAs" are actually population-based risk assessments. HIA professionals must be aware that such labelling occurs.
Building on the risk assessment work that quantifies burden of disease, cost benefit analysis of interventions is undertaken to help identify interventions that will reduce burden of disease. There are many ways to undertake such analyses and standard methods are available. Often within public health it is difficult to get the necessary information to carry out cost-benefit analyses of population-based interventions: far more information exists for individual-based interventions.
Cost-benefit information can be used in the appraisal and recommendations stages of HIA, to help understand the potential relationship between the proposal and the determinants of health, and to help identify recommendations for altering the proposal to improve health.