Seokmin Ji

Health risks associated with ambient fine particulate matter (PM _2.5 ) are well known; however, indoor exposure remains understudied. Although most people spend substantial time indoors, few studies have examined the health effects of indoor PM _2.5 owing to limited monitoring data. Even with the available data, monitoring is often limited to short periods because of financial and logistical constraints, hindering long‐term exposure assessment. To address these limitations, we leveraged our extended indoor PM _2.5 monitoring campaign to develop an optimal monitoring design that provides representative annual‐average concentrations with minimal effort. Real‐time PM _2.5 concentrations were collected in the homes of 130 participants enrolled in a Korean idiopathic pulmonary fibrosis cohort between 2021 and 2023. Our investigation included 27 participants who measured indoor PM _2.5 for at least 18 h over 4 days in each of the four seasons, constituting the complete monitoring design. To identify the optimal design, we created temporally reduced designs by selecting fewer seasons, days, and hours and compared the annual‐average concentrations of each subset with those from the complete design using the root mean square error (RMSE). Designs incorporating two mild or extreme seasons (spring–fall or summer–winter) showed lower RMSEs (3.46) compared with those from the other two‐season designs (6.18–8.88), one‐season designs (7.70–13.01), and three‐season designs (2.57–4.39). Although fewer‐day designs showed generally similar RMSEs, 18‐h designs yielded smaller RMSEs than 6‐h or 12‐h designs. Our findings suggest that indoor monitoring campaigns incorporating at least 18 h of sampling on any given day in two mild or extreme seasons can achieve representative long‐term indoor PM _2.5 concentrations in susceptible populations.

Background: South Korea’s National Health Insurance (NHI) system pursues universal health coverage, but it has not been able to alleviate patients’ financial burden owing to limited coverage and a high proportion of out-of-pocket expenses. In 2017, the government announced a plan to strengthen universality by providing coverage for all unincluded services, expanding coverage, and alleviating household financial burden. We aimed to evaluate the effect of “Moon Care” with a focus on changes in health expenditures following policy implementation, and to provide empirical evidence for future policies to strengthen the NHI system’s universality. Methods: Using data from the 2016 and 2018 Korea Health Panel (KHP), we established a treatment group affected by the policy and an unaffected control group; we ensured homogeneity between the groups using propensity score matching (PSM). Subsequently, we examined changes in NHI payments, non-payments, and out-of-pocket payments (OOP); we performed difference-in-differences (DID) analysis to evaluate the policy’s effect. Results: Following policy implementation, the control group had a higher increase than the treatment group in all categories of health expenditures, including NHI payments, non-payments, and OOP. We noted significant decreases in all three categories of health expenditures when comparing the differences before and after policy implementation, as well as between the treatment and control groups. However, we witnessed a significant decrease in the interaction term, which confirms the policy’s effect, but only for non-payments. Conclusions: We observed the policy’s intervention effect over time as a decrease in non-payments, on the effectivity of remunerating covered medical services. However, the policy did not work for NHI payments and OOP, suggesting that it failed to control the creation of new non-covered services as noncovered services were converted into covered ones. Thus, it is crucial to discuss the financial spending of health insurance regarding the inclusion of non-covered services in the NHI benefits package.