Contingent valuation of ill health caused by pollution: Testing for context and ordering effects

Contingent valuation is being increasingly used to value episodes of ill health caused by environmental pollution. In contrast to studies that have used contingent valuation to value other types of non-market goods, health episode valuation studies have tended to 1) value several ill health episodes or symptoms in the same survey, and 2) be vague in the survey instrument about the cause of the ill health, how it would be avoided or how the improvement would be paid for. The resulting values are then combined with exposure-response functions to generate economic estimates of health damages from pollution. This study tests whether episode valuation responses are sensitive to two of these design features. In a five-country study using split sample treatments, neither episode ordering nor mention of the cause of the ill health influenced stated willingness to pay to avoid specific ill health episodes.