Since the beginning of the WHO European Healthy Cities Network in 1987, the global and regional contexts for the promotion of health and well-being have changed in many ways. First, in 2000, the United Nations Millennium Goals explicitly and implicitly addressed health promotion and prevention at the global and regional levels. Second, the concern for sustainable development at the Rio Conference in 1992 was confirmed at the World Summit in Johannesburg in 2002. During the same period, in many regions including Europe, the redefinition of the roles and responsibilities of national, regional and local governments, reductions in budgets of public administrations, the privatization of community and health services, the instability of world trade, the financial system and employment, migration flows, relatively high levels of unemployment (especially among youth and young adults) have occurred in many countries in tandem with negative impacts on specific policies and programmes that are meant to promote health. Since 1990, the European Commission has been explicitly concerned about the promotion of health, environment and social policies by defining strategic agendas for the urban environment, sustainable development and governance. However, empirical studies during the 1990s show that urban areas have relatively high levels of tuberculosis, respiratory and cardiovascular diseases, cancer, adult obesity, malnutrition, tobacco smoking, poor mental health, alcohol consumption and drug abuse, sexually transmitted diseases (including AIDS), crime, homicide, violence and accidental injury and death. In addition, there is evidence that urban populations in many industrialized countries are confronted with acute new health problems stemming from exposure to persistent organic pollutants, toxic substances in building structures, radioactive waste and increasing rates of food poisoning. These threats to public health indicate an urgent need for new strategic policies and research agendas that address the complex interrelations between urban ecosystems, sustainable development, human health and well-being. The WHO Healthy Cities project is one important vector for achieving this objective at both global and regional levels.

There is a need for innovative research on housing and health. In contrast to traditional disciplinary studies, which are sector-based, interdisciplinary and transdisciplinary contributions offer a broader approach. Interdisciplinary approaches highlight the difference between a biomedical model that often adopts a symptom-treatment interpretation of housing and health and a holistic or integrated model that combines biological, cultural, economic, political, psychological and social factors in a new way. This article illustrates the pertinence of interdisciplinary contributions to develop a more holistic understanding of housing density and how it can be interpreted to understand the complex relationship between housing conditions and health status.

Urbanization, a characteristic of the twentieth century, is a profound transformation of human settlement processes and their outcomes, which has not been well understood in terms of both positive and negative impacts. This paper argues that the interrelations between urban planning, health, social, and environmental policies have been poorly articulated until now. Although sectoral approaches have often applied remedial and corrective measures to overcome unsatisfactory conditions in urban areas, today we know that infectious diseases stemming from insanitary conditions are not the leading cause of morbidity and mortality in Europe. Nonetheless diverse forms of ill health remain associated with place of work and residence. Therefore, in order to deal with the complexity and diversity of urban areas there is an urgent need to move from conventional, sectoral approaches based on biomedical models of health to coordinated action stemming from an ecological interpretation of health including its social determinants. This kind of approach is presented in order to promote health and social development at the local level.