Monetary Value of a Life Expectancy Gain due to Reduced Air Pollution : Lessons from a Contingent Valuation in France

This paper presents the results of a contingent valuation in France of the life expectancy gain due to a reduction of air pollution. A questionnaire developed by Krupnick at al. [2002] for North America was translated and administered to 300 individuals aged 40 to 75, but by contrast to the application in other countries, an open question was added after each set of bids and at the end of the questionnaire the willingness-to-pay (WTP) values were recalled to give the respondents the opportunity to correct their values. Each questionnaire was followed by detailed written debriefing to learn how the respondents interpreted the questions. Furthermore, to test the robustness of the answers and provide guidance for improving the questionnaire, five variants were tested (with about 50 individuals for each), including variants phrased in terms of life expectancy gain. That allows to evaluate the sensitivity of the answers to the bids offered, and to the way how the good is described. The results are used to provide estimates for the value of a life year (VOLY): they range from 0.020 to 0.220 M?. The wide scatter of the results is a reflection of the difficulties that the respondents have in understanding risk reductions and replying to the WTP question.