Study instrument
The questionnaires were developed based on the literature review and were revised in response to recommendations from the expert meeting. There were two versions of the questionnaire. The first version was associated with COVID-19 scenarios, whereas the second version was involved with air pollution caused by fine particulate matter, or PM2.5. Each version included the following 3 major parts: (1) socio-demographic data; (2) health status; and (3) time preferences for money and health. The questionnaires were tested for content validity based on the expert meeting’s recommendations. Following the development of all questionnaires, a face validity test was conducted.The experiment was run on a web-based computer and was developed based on a questionnaire involving time preferences for money and health (part 3 in each of the questionnaires). The web-based experiment was also tested for validity and reliability.