sentences:  In particular work has been undertaken to look at the economic value of green infrastructure, the linkage between grey and green infrastructure and also to identify areas where green infrastructure may play critical role in helping to overcome issues such as risks of flood or poor air quality.In March 2011, a prototype Green Infrastructure Valuation Toolkit was launched.The Toolkit is available under a Creative Commons license, and provides a range of tools that provide economic valuation of green infrastructure interventions.