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서울시 구로구에서 COVID-19 발생 전ㆍ후 초미세먼지(PM2.5) 농도 변화에 따른 인구집단 노출평가
김동준(Dongjun Kim),민기홍(Gihong Min),최영태(Yongtae Choe),신준섭(Junshup Shin),우재민(Jaemin Woo),김동준(Dongjun Kim),신정현(Junghyun Shin),조만수(Mansu Jo),성경화(Kyeonghwa Sung),최윤형(Yoon-hyeong Choi),이채관(Chaekwan Lee),최길용(K 한국환경보건학회 2021 한국환경보건학회지 Vol.47 No.6
Background: The coronavirus disease (COVID-19) has caused changes in human activity, and these changes may possibly increase or decrease exposure to fine dust (PM2.5). Therefore, it is necessary to evaluate the exposure to PM2.5 in relation to the outbreak of COVID-19. Objectives: The purpose of this study was to compare and evaluate the exposure to PM2.5 concentrations by the variation of dynamic populations before and after the outbreak of COVID-19. Methods: This study evaluated exposure to PM2.5 concentrations by changes in the dynamic population distribution in Guro-gu, Seoul, before and after the outbreak of COVID-19 between Jan and Feb, 2020. Gurogu was divided into 2,204 scale standard grids of 100 m×100 m. Hourly PM2.5 concentrations were modeled by the inverse distance weight method using 24 sensor-based air monitoring instruments. Hourly dynamic population distribution was evaluated according to gender and age using mobile phone network data and time-activity patterns. Results: Compared to before, the population exposure to PM2.5 decreased after the outbreak of COVID-19. The concentration of PM2.5 after the outbreak of COVID-19 decreased by about 41% on average. The variation of dynamic population before and after the outbreak of COVID-19 decreased by about 18% on average. Conclusions: Comparing before and after the outbreak of COVID-19, the population exposures to PM2.5 decreased by about 40%. This can be explained to suggest that changes in people’s activity patterns due to the outbreak of COVID-19 resulted in a decrease in exposure to PM2.5.
PHMG (polyhexamethylene guanidine) 흡입독성참고치 산출을 통한 가습기살균제 노출등급 분류 및 특성
김은채(Eunchae Kim),류현수(Hyeonsu Ryu),박진현(Jinhyeon Park),최영태(Youngtae Choe),허정(Jung Heo),이슬아(Seula Lee),조은경(Eun-Kyung Jo),최윤형(Yoon-Hyeong Choi),조만수(Mansu Cho),양원호(Wonho Yang) 한국환경보건학회 2020 한국환경보건학회지 Vol.46 No.3
Objectives: The Korean Ministry of Environment has identified cases of people suspected of suffering lung disease potentially caused by polyhexamethylene guanidine (PHMG) used in humidifier disinfectants (HDs). Exposure assessment for the HDs was conducted using a questionnaire during face-to-face interview. The main purposes of this study were to develop a methodology to effectively classify levels of exposure to HDs based on a questionnaire. Methods: We first identified the overall participants’ exposure characteristics by HD exposure levels; Second, we selected misclassified subjects and investigated characteristics of overestimated and underestimated subjects, focusing on exposure cases to PHMG-containing HDs. An inhalation reference concentration (RfC) for PHMG was produced on the basis of inhalation toxicity values. We made a cross-tabulation of the exposure classes (Exposure classes 1-to-4) by clinical classes based on the RfC. When the value of the exposure class minus the clinical class was 0 or 1, we assumed these were true values. When the value was ≥2 and ≤ −2, we assigned these cases to the overestimation group and underestimation group, respectively. Results: The overestimated group may have already recovered and responded excessively due to psychological anxiety or in order to receive compensation. On the other hand, relatively high mortality rates and surrogate responses for those under 10 years of age may have resulted in inaccurate exposure assessment for underestimated groups. For the characteristics of exposure, it was shown that for the underestimated group, the exposure was relatively weaker than the overestimated group, even though a high overall clinical rating was determined. Conclusions: This study may suggest ways to reduce bias and overcome the limitations of current HD exposure assessment.