We measured PM2.5 in 41 underground shopping districts (USDs) in the Seoul metropolitan area from June to November 2017, and associated 18 trace elements to determine the sources and assess the respiratory risks. The PM2.5 concentrations were 18.0 ± 8.0 μg/m3 inside USDs, which were lower than 25.2 ± 10.6 μg/m3 outside. We identified five sources such as indoor miscellanea, soil dust, vehicle exhaust/cooking, coal combustion, and road/subway dust, using factor analysis. Almost 67% of the total trace element concentration resulted from soil dust. Soil dust contribution increased with the number of stores because of fugitive dust emissions due to an increase in passers-by. Vehicle exhaust/cooking contribution was higher when the entrances of the USDs were closed, whereas coal combustion contribution was higher when the entrances of the USDs were open. Although miscellanea and coal combustion contributions were 3.4% and 0.7%, respectively, among five elements with cancer risk, Cr and Ni were included in miscellanea, and Pb, Cd, and As were included in coal combustion. The excess cancer risk (ECR) was the highest at 67 × 10−6 for Cr, and the ECR for Pb was lower than 10−6, a goal of the United States Environmental Protection Agency for hazardous air pollutants.

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Various pollutants are emitted and released during cooking, smoking, cleaning, and building materials in indoor environments. Indoor air quality management in kitchens is important because a considerable amount of pollutants are produced by the high temperature and combustion conditions associated with the cooking process. In this study, the correlation between the concentration characteristics of several indoor pollutants generated during cooking, and the detected concentration of these pollutants is investigated based on the ventilation pattern. When liquefied natural gas was burned for one hour without ingredients, the levels of CO and NO 2 were 6-7 times higher compared with the background concentration due to incomplete combustion. When fish was roasted, PM 2.5 concentration was approximately three times higher compared with when meat was roasted. However, the level of gaseous pollutants was higher for the latter. Based on the evaluation of the ventilation effect during the operation of the range hood, the concentration of particulate and gaseous pollutants (CO, NO 2 ) was approximately ten times lower compared with the off state. In addition, when the hood is turned off, the time taken to decrease the concentration in the pre-cooked state is five hours or more, indicating that ventilation is necessary for indoor cooking.

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