This study investigated the characteristics and sources of PM 2.5 at Gimpo Airport, Korea, through simultaneous indoor and outdoor sampling conducted during the summer of 2016. The average PM 2.5 concentrations were 32.9 ± 14.5 μ g/m 3 in the arrival waiting room (AWR), 29.2 ± 13.3 μ g/m 3 in the departure waiting room (DWR), 35.2 ± 19.3 μ g/m 3 at the bus stop, and 31.5 ± 18.7 μ g/m 3 on the runway. The indoor‐to‐outdoor ratios were 1.06 for the AWR and 0.96 for the DWR, indicating that significant amounts of outdoor pollutants entered the indoor spaces near entrances with high passenger flow, where they accumulated and were resuspended. Chemical component analysis revealed that secondary inorganic ions (NO 3 − , SO 4 2− , and NH 4 + ) were dominant at all sites. Through positive matrix factorization (PMF), seven sources were identified: secondary nitrate, secondary sulfate, miscellanea, soil, vehicle emission, indoor sources, and oil combustion. Secondary aerosols contributed approximately 40% of indoor PM 2.5 and over 50% of outdoor PM 2.5 . Outdoor air showed a high contribution from combustion‐related and miscellaneous sources, whereas indoors, soil and indoor sources were significant contributors. At bus stops, traffic‐related components such as Ba were prominent, while runways were impacted by SO 2 oxidation resulting from aircraft exhaust. Meanwhile, indoor air exhibited elevated levels of components associated with building materials and resuspension caused by human activities. These results reflect the unique operational and structural characteristics of airport terminals, emphasizing that PM 2.5 levels within airports are determined by the combined effects of outdoor inflow and indoor emission processes. This study provides essential foundational data to improve air quality management at airports—public‐use facilities used by many passengers—and underscores the necessity of an integrated strategy that addresses both indoor and outdoor environments.
Won et al. (2026) studied this question.