Costa Rica's economy relies on a robust ecotourism industry, and the care it takes for its environment shows. The Central American country ranks fifth in the global Environmental Index, a rating that should only improve as it strives to become carbon-neutral by 2021. Costa Rica has avoided the deforestation that ravages some Latin American countries: the country earns a score of 97 or better in the categories of forestry, air pollution and climate change.
Source: http://www.forbes.com/2009/04/15/worlds-cleanest-countries-business-energy-clean-countries_slide_5.html?thisSpeed=15000