In June 1992, the Rio Earth Summit declared that “the right to development must be fulfilled so as to equitably meet developmental and environmental needs of present and future generations”. This was based on the Brundtland Report that raised increasing concerns about the effect of economic development on health, natural resources and the environment (World Commission on Environment and Development, 1987). It clarified that sustainable development was not just about the environment, but also the economy and the society. The summit produced a comprehensive blueprint of action, known as Agenda 21, to be taken globally, nationally and locally by organizations of the UN, governments, and major groups in every area in which humans directly affect the environment. The 178 countries that signed Agenda 21 were encouraged to implement sustainable development from the local to national to regional levels.