Abstract
With increasing Internet coverage, the use of a web-based survey for epidemiological study is a possibility. We performed an investigation in Japan in winter 2008 using the web-based daily questionnaire for health (WDQH). The WDQH is a web-based questionnaire survey formulated to obtain information about the daily physical condition of the general public on a real-time basis, in order to study correlations between changes in physical health and changes in environmental factors. Respondents were asked whether they felt ill and had specific symptoms including fever. We analysed the environmental factors along with the health conditions obtained from the WDQH. Four factors were found to influence health: minimum temperature, hours of sunlight, median humidity and weekday or holiday. The WDQH allowed a daily health survey in the general population in real time via the Internet.
Acknowledgements
This study was conducted with the support of a Health and Labour Sciences Research Grant. We are grateful to numerous people including the Ministry of Health, Labour and Welfare for their considerable cooperation during the preparation of this article. We also thank Y. Miyake and M. Yoshimura for their assistance in the statistical analysis.