코로나19 집단감염 사례 기반 잔류 에어로졸의 공기전파 위험도 평가 및 자연환기 효과 분석

초록

.This study investigated residual aerosol characteristics and airborne transmission risk in a classroom associated with a COVID-19 cluster outbreak. Field experiments were conducted in an actual language institute classroom where a cluster infection occurred in 2021. The research focused on the possibility of time-shift airborne exposure caused by residual aerosols remaining after the conclusion of class. Droplet-like particle experiments were performed under actual classroom operating conditions consisting of a 55-minute class period and a 5-minute break period. Aerosol behavior and concentration changes were analyzed under two conditions: opening the door and natural cross-ventilation through simultaneous opening of windows and doors. The results showed that approximately 74% of the droplet-like particles remained in the classroom after the 5-minute break period when only the door was opened. Based on the measured residual aerosol concentration, the airborne infection risk estimated using the Wells-Riley model was 29.31%. In contrast, under natural ventilation conditions, the infection risk decreased to 3.04%, demonstrating significant aerosol removal and risk reduction effects. These findings suggest that limited ventilation during short break periods may be insufficient to remove residual aerosols in educational facilities, while natural cross-ventilation can effectively reduce airborne transmission risk associated with residual aerosols.

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