BACKGROUND: With the aim to prevent sick building syndrome and worsening of allergic symptoms, primarily resulting from the indoor environment, the relationships among people's residential environment in recent years, their lifestyle habits, their awareness, and their symptoms were investigated using an online survey. METHODS: In the survey, respondents experiencing symptoms specific to sick building syndrome, although they were not diagnosed with sick building syndrome, were categorized in the pre-sick building syndrome group. The relationships among individual characteristics, residential environment, and individual awareness were analyzed. RESULTS: Results showed that the prevalence of pre-sick building syndrome was high among young (aged 20-29 years) population of both sexes. In addition, "condensation," "moisture," "musty odors" in the house, and the "use of deodorant and fragrance" were all significantly associated with pre-sick building syndrome. Conversely, there was no significant association with recently built "wooden" houses that are highly airtight and have thermal insulation. CONCLUSIONS Efficient "ventilation" plans and "ventilation" improvement and air conditioning systems to prevent mold and condensation in rooms are necessary to maintain a good, indoor environment that is beneficial for health. Efforts should also be made to encourage individuals to regularly clean and effectively ventilate their homes.