Integrated assessment is the attempt to assess complex, real-world problems in a way that can help policy-makers and other stakeholders make better, more informed decisions about how to act.

Integrated assessment can be used to analyse almost any type of problem. In the past, the main applications have been in relation to broad-scale environmental issues, such as climate change, air pollution, land use change or catchment management. In the INTARESE project we are extending integrated assessment to the analysis of environmental health issues. We refer to this more specifically as "integrated environmental health impact assessment'.

Although the term is sometimes used to mean the ‘health of the environment', the more accepted meaning (and the one used in Intarese) relates to environmental effects on human health. It is thus used to include any factor that operates through the environment to affect human health - for example, pollution in all its forms (and in the indoor as well as outdoor environment), natural hazards (earthquakes, storms, floods etc), vector borne diseases (e.g. malaria, avian flu) and physical risks such as traffic accidents or fires.

Traditional risk assessment has generally focused on assessing the potential for damage to human health from individual substances (especially chemicals) or situations. As such it has tended to be rather narrow in its concerns and to consider only more immediate risk factors. The INTARESE approach is designed to be much more inclusive and integrated. Its aim is not to determine whether there may be risks from individual hazards, but to assess the burden of disease attributable to major environmental factors, and the impacts on health of policies or other broad-scale interventions.

As such, the INTARESE approach has five important characteristics that distinguish it from traditional risk assessment:

1. it is focused on policies;
2. it is systemic in approach - i.e. it deliberately analyses complex, multi-factorial issues;
3. it considers beneficial as well as adverse effects of any situation or intervention;
4. it is based on a ‘full-chain' analysis - i.e. it considers the complete causal web from sources to health impacts;
5. results of assessments are additive, in that different causes and effects can be summed to provide a measure of the overall net impact on health.

The INTARESE approach is intended to be used to assess any policy-relevant problem that has implications for environmental health. Not all problems necessarily need an integrated approach: where the issue is simple and effects on health relatively direct, traditional forms of risk or health impact assessment are likely to be more appropriate. Where problems are multifactorial and complex, however, more integrated methods of assessment are likely to be beneficial. Examples include (but are not limited to): climate change, urban develoment, agriculture, transport, waste management, energy policy, water management, air pollution, housing policy and food safety.

Many of the problems that now confront society are complex and multi-facetted.  They often operate at broad regional or global scales; they often result from the interplay between different factors; they may come under the responsibility of different agencies and authorities; they typically have long-term and important consequences for human health.  In addition, many of these problems derive from, and in turn affect, different aspects of society - e.g. economies, social stuctures, human well-being and international security.  They thereby affect many different stakeholders at many different levels.  In order to address these types of problem, methods of assessment are needed that bring together all the different interests, agencies and stakeholders.