Unfortunately, to our knowledge, direct estimates of Mexican WTP for reductions in the health endpoints considered in this paper are not yet available. Therefore, we use WTP parameters (for adult respiratory symptom days, adult reduced activity days, asthma attacks, and chronic bronchitis) that are based on . studies. But given that average income adjusted for purchasing power parity is approximately four times as high in the United States as in Mexico, Mexican WTP may be lower than American WTP. Cultural factors may also cause WTP in the two countries to differ. To account for international differences.
