This study investigated indoor air quality (IAQ) in 302 facilities (consisting of 638 monitoring points) across five types of multi-use facilities for the health of vulnerable populations in Seoul. The facility types consisted of the following: ICPs (indoor children’s playgrounds), PCCs (postnatal care centers), ECFs (elderly care facilities), HCFs (health care facilities), and CCCs (child care centers). The investigation was carried out over a 1-year period, from January to December 2024. The objective of this research was to provide a scientific basis for IAQ management by identifying characteristics specific to facility types and potential risk levels for vulnerable populations in Seoul. Five indoor air pollutants (PM10, PM2.5, CO2, HCHO, and TAB) were continuously measured, and their concentration distributions, temporal variability, and multi-pollutant patterns were analyzed using data visualization and statistical methods. Boxplots and ridgeline plots characterized distributions and seasonality by facility type, while star plots and K-means clustering were used to examine multi-pollutant combinations and inter-facility pattern differences. Most measurements were within national IAQ standards. However, HCFs and PCCs exhibited relatively higher mean levels and variability of HCHO and TAB, indicating a greater need to control chemical and microbiological sources. CO2 concentrations approached or temporarily exceeded the national standard, particularly in HCFs, reflecting differences in occupant density, occupancy time, and ventilation management. Kruskal-Wallis and pairwise Wilcoxon rank-sum tests revealed statistically significant differences among facility types, particularly for CO2 and HCHO, consistent with the visualized multi-pollutant profiles. K-means clustering identified three IAQ patterns-multi-pollutant-elevated, activity/ventilation-influenced, and low-pollutionindicating that management needs may vary across facilities despite uniform national standards. These findings provide a methodological basis for IAQ big data analysis, policy making, and supporting future research integrating multi-year, outdoor, building, activity, and health data.

This study measured the suspended fungal concentration in indoor multiple facilities nationwide. The regions were selected as representative cities by region: Seoul, Gyeonggi (Incheon), Gangwon, Gwangju, Daejeon, and Busan. A total of 2028 regional comparisons, including department stores, schools, public toilets, libraries, and banks, subway, sports facilities and comparative analysis were conducted for each multi-use facility industry. Among the nationwide, Among the regions, the average concentration of floating mold in indoor multi-use facilities was the lowest in Busan at 394.67 CFU/m3, followed by Gyeonggi and Incheon 487.90 CFU/m3, Seoul 542.84 CFU/m3, Daejeon 809.30 CFU/m3, Gangwon 1,145.22 CFU/m3, Gwangju was 1,371.10 CFU/m3 in the order. Busan was the lowest, and Gangwon was the highest. The reason that Busan, which has a high average temperature and population density, shows a lower mold concentration than Gangwon, is that floating mold in the indoor air is not affected by the external atmospheric environment, population density, and number of facility users. Although it cannot be said that there is no influence of the atmospheric environment, it was found that the indoor environment has different characteristics from the outdoor environment. The importance of air quality management has been confirmed, and further, it is necessary to subdivide the management standards by region and multi-use facilities, and the management standards need to be converted to maintenance rather than recommendations.

In this study, indoor air quality indices (IAQI-C and IAQI-E) were developed for child care centers and elderly care centers based on health effects, and compared to the air quality index (CAI) for outdoor atmosphere. In addition, composite indices that integrate individual indices for each pollutant were developed to quickly and conveniently recognize the current air quality. Among all data, 71.2% and 35.6% belonged to the grades 'Good' and 'Moderate' for child care centers and elderly care centers, respectively. This assessment is more stringent than the CAI's criteria.

Radon is known to be one of the representative carcinogen materials, and may cause severe health damage to the human body with long-term exposure. Without proper treatment such as natural and mechanical ventilation, indoor radon concentration tends to increase as time passes. In this aspect, it is necessary to maintain indoor radon concentration below the domestic indoor air quality (IAQ) management standard by continuous monitoring. However, the number of practical devices which can detect radon concentration is scarce and most of the existing devices are very costly. Among such devices, the RS9A, a prototype of a radon detector, detects indoor radon concentration and is priced significantly lower compared to other existing radon detectors. In this paper, we investigated the RS9A for the continuous detection of indoor radon gas and compared its performance to a commercially available radon detector (RadonEye). We measured indoor radon concentrations at two separate sites by using both detectors simultaneously. The indoor radon concentrations measured by the aforementioned detectors revealed a high correlation. Therefore, the RS9A can be considered as an appropriate candidate for use as a continuous indoor radon monitoring system.

In this study, the distribution of each facility group, the pollution level of local municipalities and the status of self-measurement were investigated and analyzed using data provided by the Ministry of Environment. It was found that most of the workplaces to be managed are facilities of sensitive class, indoor parking lots and largescale stores. The results of the survey on the total pollution level by facility group showed that the rate of contamination was the highest in the facilities where there are many sensitive users, including the subway station and the underground shopping malls. Through self-measurement, in the case of fine particle matter, it was found that it was present in amounts of 51.71 μg/m3, 50.72 μg/m3, 44.47 μg/m3 and 54.44 μg/m3 in medical institutions, day care centers, elderly care facilities and postnatal care centers, respectively. Also, there were facilities exceeding the standard in the medical institutions. However, most of the pollutants in the facilities surveyed by the municipality are higher than the self-measured concentrations, so it is necessary to examine the cause of such pollution.