Iceland has been ranked as the most environmentally clean country the world, according to the latest Environmental Performance Index.
The study, conducted by Yale and Columbia universities, rated 163 countries based on factors such as air and water quality, greenhouse gas emissions, ecosystem diversity and envionmental public health. Out of the 25 indicators, Iceland scored 93.5 out of 100. It is followed by Switzerland and Costa Rica. Sierra Leone ranked last with a score of 32.1.
The assesment is based on how closely governments are following environmental policy regulations. Countries who ranked highest on the list are those who have diverse ecosystems, a rich supply of fresh water and little industrial contamination, and wealthy countries who have made the most improvement at environmental restoration.
The recent eruption of Eyjafjallajökull will not be taken into account when the study is next conducted in 2012, as it does not take into account emissions caused by natural disasters, only fuel usage.
The full results of the study and methodology is available online here.