Evaluation of the costs and outcomes associated with environmental policies and interventions is often required to inform public policy and allocate scarce resources. Methods to conduct assessments of cost-effectiveness have been developed in the context of pharmaceuticals, but have more recently been applied in public health, diagnostics, and other more complex interventions. The suitability of existing economic evaluation methodology has been explored in many contexts, however, this is yet to be undertaken for interventions and policies pertaining to the natural environment, such as urban green spaces and strategies to reduce indoor and outdoor air pollution. To make significant inroads into the evaluation of interventions and policies relating to the natural environment requires an understanding of the challenges faced in this context. Many of these challenges may be practical (data-related), however, a number are also methodological, and thus have implications for the appropriate framework for economic evaluation. This paper considers some of the challenges faced when conducting cost-effectiveness analyses in this context and explores what solutions have been proposed thus far. The intention is to help pave the way for consideration of which existing framework is most appropriate for the evaluation of natural environment (NE) interventions, or if a distinct framework is required. Environmental policies and interventions relating to the built environment, for example, housing, are not explicitly included here.
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