NEW YORK -- Finland's clean air and water make it the most environmentally-sustainable country on the planet, according to a 142-nation study released Monday, which puts United Arab Emirates in last place, AFP said. The environmental sustainability index (ESI) was drawn up by Colombia and Yale universities and a special task force of the World Economic Forum, which is meeting here. "Finland's place at the top of the ESI 2002 ranking is due to its success in minimizing air and water pollution, its high institutional capacity to handle environmental problems and its comparatively low levels of greenhouse gas emissions," said a forum statement. The study ranked the United States as 51st and the United Arab Emirates last. "The United States' performance is uneven," the statement said. "The United States lags in controlling greenhouse gas emissions that contribute to climate change and under-performs its peers in reducing waste," it said. "Yet, the United States stands at the forefront of the world in controlling water pollution and promoting robust environmental policy debates." Among the 20 factors taken into account are urban air quality, water and the strength of environmental regulation. The United States has refused to endorse the 1997 Kyoto Protocol, which aims to bind developed countries to legally enforceable reductions of so-called greenhouse gas emissions blamed for global warming.