The Analysis of Factors Affecting the Personal Exposure to Nitrogen Dioxide. Y. Chung, J. Lee, D. Shin, and J. Yang, Dept. of Prev. Med. and Inst. for Environ. Research, College of Medicine, Yonsei University, Seoul, Korea
An international study of the personal exposures to nitrogen dioxide (NO2) was conducted in 17 cities in 13 countries under the same research scheme. We measured NO2 concentrations using a passive sampler developed by Yanagisawa et al. (1982) for 31 individuals during two-day winter periods. In order to figure an outline of contributions that different sources made to the personal exposure to NO2, we also estimated those NO2 concentrations from separate samplers located at indoor, outdoor and workplace in Seoul, Korea for the same periods. In addition to these measurements, each study participant were asked to report a daily activity diary as well as a questionnaire including questions of identifying the sources of potential NO2 exposure. A participant was asked to report his/her activity pattern at half-hour time bands during the day. Questions regarding experience of respiratory symptoms, information on commuting types and time, types of home heating systems, and house characteristics were also included in the questionnaire. The NO2 measurements in all participated cities were presented at Indoor Air 1996. In terms of both outdoor and indoor exposure, the highest 48-hour cumulative NO2 concentrations were measured in Seoul (50.6 ppb and 43.2 ppb, respectively). For the personal exposure, the 48-hour cumulative concentration was 47.9 ppb which is the second highest among 17 cities. In Seoul, Korea, we found that the important factors affecting the variation of NO2 concentrations in indoor were the presence of smokers at home, use of a stove using hydrocarbons fuel and the type of ventilation. Personal NO2 levels were found to be affected by the presence of smokers, use of a stove using hydrocarbons fuel and the type of ventilation. The NO2 concentrations measured from passive smokers were higher than that from non-passive smokers in personal, indoor and outdoor exposure. Individual NO2 exposure levels of participants who experienced a respiratory symptom were lower than that of the group who did not experience a respiratory symptom during the diary study. We correlated personal exposure levels with those measured at indoor or outdoor. We compared NO2 levels from a personal sampler with an estimated total personal exposure levels based on the levels from indoor and outdoor sampler. As we estimated a total personal exposure level, we were used to the daily activity patterns as well. This study offered an opportunity of estimating NO2 levels and comparing these with those from other counties. We also assessed the impact of those factors (daily activity patterns, experience of respiratory symptoms, and information on commuting types and time, types of home heating systems, and house characteristics) on the personal exposure NO2 level in Seoul, Korea.