What are some revealed and stated preference techniques you can use when addressing the environmental problem of excess Co ₂ build up due to vehicles? What assumptions can be made to warrant the use of a particular technique? What would be the best method/technique to use for a study such as this study and why?

What is the main use of the type of valuation method (consumptive value or non-consumptive value), and why is it of use in the larger economic situation? Could additional methods be used to study the impacts of this situation? Why are they the most appropriate way of measuring the impact identified?