Personal or population exposure to hazardous air pollutants has often been assessed by time-weighted average model with combining concentrations of indoor environments and time-activity pattern, which were mainly a single measurement. However, daily levels of air pollutants in indoor environments may greatly be changed because of source emission, ventilation, decay rate and so on. Subsequently exposure by a single measurement in indoor environments could not be assessed properly. In this study, we measured the consecutive 21 daily indoor and outdoor measurements of nitrogen dioxide (NO₂) with 37 houses and 19 shops such as restaurants and coffee shops beside street by using of passive samplers. Considering that average concentration during 21 days was true value, paired t-test was conducted. Daily variations of NO₂ in houses with constant or low emission source were different from those in restaurants with irregular or high emission source. These results can be explained that the NO₂ emission of indoor sources could affect the validity of measurement periods.

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• 김동건
• 양원호