Recent analysis has shown, for example, that the economic cost of outdoor air pollution, in terms of the value of lives lost and ill health, is much higher than previously thought. While costs were estimated at 4% of Gross Domestic Product (GDP) in OECD countries on average in 2010, China faced costs that were estimated at the equivalent of 12% of GDP. Further work is underway to assess the economic consequences of risks posed by climate change, air pollution and the link between land, water and energy. Cost-benefit analysis that includes economic valuation of environmental externalities is a key tool available to comprehensively consider both the economic and environmental consequences of policies. Securing sources of finance to support green growth is even more challenging in developing countries (2014c).