Prescriptive scenarios

The text on this page is taken from an equivalent page of the IEHIAS-project.

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Prescriptive scenarios specify the conditions under which the issue will be assessed in a fixed and usually static form. Depending on the purpose of the scenario, the information may relate to almost any part of the causal chain (from sources to health outcome); often, however, the focus is on the links between source and exposure.

Examples might thus be:

• air pollution: a reduction in the maximum daily 8 hourly ozone concentration to < 100 ug/m3;
• emission controls: a 10% reduction in emissions of PM2.5 from road vehicles;
• consumer safety: reduction in concentrations of toluene to equivalent of <0.1% in adhesives and spray paints on sale to the general public

In each case, the assessment would consider the downstream impacts of these conditions on health, but would not consider how the conditions would be achieved (e.g. what technological or socio-economic changes would be necessary), nor the implications of these changes.

Assessments based on prescriptive scenarios thus focus only on the direct effects of policy (or other specified) actions. In doing so, they ignore behavioural and dynamic processes, and therefore many secondary or lower order impacts.