## 1 Introduction  
In recent years, particulate matter (PM) has emerged as a big problem in Korea. According to the Organization for Economic Cooperation and Development (OECD)'s annual report on the concentration of ultra-particulate matter in countries by 2017, the mean population was exposed to PM\({}_{2.5}\) and with pollution at 25.1 \(\mathrm{\SIUnitSymbolMicro m}\)\({}^{3}\), Korea was the second worst of the member countries [1], with a level twice as high as the average OECD member countries (12.5 \(\mathrm{\SIUnitSymbolMicro m}\)\({}^{3}\)) and 2.5 times higher than the World Health Organization (WHO)'s annual average recommended concentration (10 \(\mathrm{\SIUnitSymbolMicro m}\)\({}^{3}\)). Based on Korea's PM forecast, the number of \"bad\" (36-75 \(\mathrm{\SIUnitSymbolMicro m}\)\({}^{3}\)) and \"very bad\" (more than 76 \(\mathrm{\SIUnitSymbolMicro m}\)\({}^{3}\)) days in metropolitan areas increased from 62 in 2015 to 77 in 2018 [2]. In early March 2019, Korea experienced the most severe PM situation. In Seoul, an 8-day ultra-particulate matter warning (PM\({}_{2.5}\) with a time-averaged concentration of more than 75 \(\mathrm{\SIUnitSymbolMicro m}\)\({}^{3}\) for 2 h) and 2 days (March 5 and 6) with an alert level (an average PM\({}_{2.5}\) of more than 150 \(\mathrm{\SIUnitSymbolMicro m}\)\({}^{3}\) for 2 h) [3]. As a result, the PM levels became hazardous to health. PM is a WHO Level 1 carcinogen that has negative effects on health, contributing to cardiovascular and respiratory diseases [4; 5]. [PERSON] and [PERSON] [6] investigated the effect of particulate emissions on specific diseases in Seoul and found that the number of hospitalizations for various respiratory diseases increased as the amount of ultra-PM increased. Korea's increase in PM is related to rapid economic growth. Large cities, such as Seoul, have high levels of energy use resulting from the concentration of population and economic activity and their direct emission of air pollutants is high. Further, since its geographical location is on the mid-latitude westerly wind area, seasonal influx of PM from neighboring China also affects the increase of PM in Korea [7]. According to the survey data on the perception of environmental problems among Koreans aged 13 and over, conducted by the Korea National Statistical Office (KNSO), 82.5% of respondents experience anxiety about PM [8]. [PERSON] et al. [9] observed that Koreans regard PM as the most serious social risk factor. Because national concern about PM has been increasing, the government introduced a comprehensive plan for PM in 2017. In 2018, it attempted to reduce PM emissions by enforcing a Special Act on Particulate Matter in major cities across the country, including the capital region [10]. The Ministry of Environment, in consideration of atmospheric environmental standards and health effects, produced a PM forecasting system, which presents the levels of PM as well as countermeasures [11]. However, despite the various risk indicators for PM and notwithstanding the government measures, the residents of Seoul are notably passive in protecting individuals and society from PM despite viewing it as a threat [12]. To prevent and reduce the PM generated by anthropogenic rather than natural factors, public efforts must be accompanied by measures at the national level. Without ensuring that residents understand PM, it is predicted that reduction measures will be ineffective. Therefore, this study aims to identify levels of awareness of PM, recognition of indoor air quality, symptoms of PM exposure experienced by residents and coping behavior in relation to PM in Seoul. Specific research questions are as follows:  
First, how do residents perceive the indoor air quality, how do they feel PM symptoms and how do they behave in response to PM? Second, do the different characteristics of residents produce any variations in behavior in response to PM? Third, what are the impediments to the proper responses to PM by residents?