Knowledge in the field of environmental health remains segmented and incomplete, but growing rapidly. Within the context of external factors that define its boundaries, environmental health has evolved over time into a complex, multidisciplinary and ill-defined field with uncertain solutions. Many of the key determinants and solutions to environmental health lie outside the direct realm of health and are strongly dependent on environmental changes, water and sanitation, industrial development, education, employment, trade, tourism, agriculture, urbanization, energy, housing and national security. Environmental risks, vulnerability and variability manifest themselves in different ways and at different time scales. While there are shared global and transnational problems, each community, country or region faces its own unique environmental health problems, the solution of which depends on circumstances surrounding the resources, customs, institutions, values and environmental vulnerability. This work will contain critical reviews and assessments of environmental health practices and research that have worked in places and thus can guide programs and economic development in other countries or regions.

Environmental health draws upon the methods and findings of many established academic disciplines, from clinical medicine to epidemiology, chemistry and biology to toxicology, economics to political science and ethics. The interdisciplinary nature of the pursuit underscores the need to synthesize the results of increasingly narrow academic disciplines and to incorporate their contributions into a big-picture understanding of the dependence of our health on the environment. Integrative assessment, whether qualitative or quantitative, is a useful approach in environmental health. This work seeks to conceptualize environmental health more clearly, to describe the best available scientific methods that can be used in characterizing and managing environmental health risks, to extend the field of environmental health through new theoretical perspectives and heightened appreciation of social, economic and political contexts, and to encourage a richer analysis in the field through examples of diverse experiences in dealing with the health-environment interface. The approach is to avoid gloom and doom and instead provide a framework for further research that is based on valuable ideas and experiences from different parts of the world.

With some categorical threats, it may be possible to establish clear causal linkages and effects but where the health hazard is the result of environmental change, the risk bundles are likely to embrace interactions among streams of fundamental human processes including public policies, economic activities, technological applications, and varying lifestyles. Dealing with environmental risks invariably involves coping with the uncertain, the unknowable and the inherently indeterminable. The situation is not helped by the fact that mechanisms relating development hazards, environmental exposures and health are generally lacking and integrated databases and information systems to support policy and decision-making, planning and evaluation are rarely available at relevant spatial and time scales. A lot of the environmental health programs and policies have therefore been driven by political expediency, scientific weight of evidence or precautionary principles rather than based on sound scientific principles. This work will be guided by the need to (i) provide a comprehensive overview of the existing and widely scattered knowledge base in the emerging field; (ii) place environmental health and risks in the broader context of environmental change and associated ecological, political, economic, social and cultural drivers of the change; (iii) identify and assess potential interventions to prevent or remediate the risks; and (iv) define priorities for further research.

The Encyclopedia of Environmental Health will contain numerous examples of policy options and environmental health practices that have worked and thus can guide programs in other countries or regions. It will include a wide range of tools and strategies that can assist communities and countries in assessing environmental health conditions, monitoring progress of intervention implementation and evaluating outcomes.