Costa Rica continues its recent streak of winning high praise for its environmentalism.  An April 15th article in Forbes magazine named The World’s Cleanest Countries, using measurements such as:

EPI’s environmental health ranking, which measures the effects of pollution on human health. A second broad measure, ecosystem vitality, measures the health of fisheries, the amount of  green house gases a country pumps into the air and how well it preserves the diversity of its plants and animals.

Costa Rica is mentioned in the article.  A few developing nations break into the top 10 of the rankings. Costa Rica has a per-capita gross domestic product of $11,600, but ranks fifth overall as it protects its forests and rich biodiversity, both lures for ecotourists.
The study was conducted in collaboration with Environmental Performance Index (EPI), Columbia University’s Center for International Earth Science Information Network, and Yale University’s Center for Environmental Law and Policy.

http://www.forbes.com/2009/04/15/worlds-cleanest-countries-business-energy-clean-countries.html

Learn about Sustainable Development In Costa Rica