Monetary valuation is increasingly used to support decision process, often relying on economic criteria. This work aims at determining the reliability of monetary valuation of health impact by analyzing the influence of providing the causes of the valued health impact in the contingent valuation.

Economic theory states that only the consequences of a health impact should influence its value, and not its causes. However, it also recommend providing respondents with enough information to take an informed decision. In practice, various approaches have being taken with not really consistent consequences.

A contingent valuation was conducted to observe the effect of indicating the causes of chronic obstructive pulmonary disease, with four levels of information: no cause provided, the causes are said to be mainly smoking and air pollution, the cause is said to be air pollution only, and smoking only. The analysis of respondents' behaviors highlight that providing the possible causes increases the acceptability of the questionnaire but does not influence the value itself, personal characteristics of the respondents being more important (healthy diet, sport practice, pollution in living area).

To conclude, providing information about the causes of the valued health impact would increase the reliability of the assessment. However, values determined with no or other causes may still be used, as causes does not influence it.