Participants of this cross-sectional study were market workers and shoppers in traditional markets located in northeastern and central Taiwan. As described in the Introduction, there were major AI outbreaks in Kaohsiung (in southern Taiwan), and therefore, the current study aimed to explore the risk perception about AI, as well as the recommended AI preventive behavior, among traditional market workers and shoppers in central and northeastern Taiwan, where there have not been reported AI outbreaks. Accordingly, two traditional markets were selected in central Taiwan and two others were selected in northeastern Taiwan. Since this study sought to examine simultaneously both groups of participants (i.e., traditional market workers and shoppers), we decided to interview market workers and shoppers with a one-to-one ratio. With this particular purpose in mind, purposive sampling was employed in traditional markets: market workers were interviewed by trained interviewers during their breaks; because there were far more market shoppers than workers, market shoppers were randomly selected for an interview at the market entrance if they happened to step into the market when an interviewer just became available to conduct a survey after completing the previous interview. The interviewer-administered survey using a structured questionnaire was conducted in December 2009 through January 2010. A total of 352 anonymous interviews were completed with a response rate of 95.1%. Each interview was conducted by a trained interviewer and took the participant 5-10 minutes to complete the questionnaire. Traditional market workers and shoppers were first approached and informed of the study's goals and procedures by our interviewers to obtain verbal informed consent before each interview. Every attempt made to approach potential participants, be it successful or unsuccessful, was documented in order to calculate the response rate. We also provided a gift worth approximately US $1 as incentives to increase the response rate. The study protocol and verbal consent procedure were reviewed and approved by the Institutional Review Board of the National Taiwan University College of Public Health.