Changes in indoor VOC and aldehyde concentrations in newly built unoccupied apartments following regulations in South Korea.

Volatile pollutants are commonly detected in the indoor environments of newly constructed buildings, and high concentrations can adversely affect the health of occupants. The Indoor Air Quality Control Act (IAQCA) has been implemented in Korea to reduce indoor volatile organic compounds (VOCs) and aldehydes in newly constructed apartments. However, research on its long-term effects remains limited. This study aimed to evaluate the changes in the concentrations of these pollutants following the enforcement of the IAQCA. A total of 528 newly constructed apartment units were analyzed before occupancy and categorized into three periods-pre-implementation of IAQCA (Pre), immediate post-implementation of IAQCA (Post I), and 11 years post-implementation of IAQCA (Post II). 41 individual VOCs, total volatile organic compounds (TVOC), and five aldehydes were measured. Among the three periods, the concentrations of most volatile pollutants were the highest in the Pre period. The median concentration of formaldehyde was 173 μg/m3 in Pre, 102 μg/m3 in Post I, and 41.3 μg/m3 in Post II, presenting statistically significant differences across the periods (p < 0.001). Similarly, the median concentration of toluene was 668 μg/m3 in Pre, 386 μg/m3 in Post I, and 197 μg/m3 in Post II, with statistically significant differences (p < 0.001). In contrast, the median styrene concentration did not significantly change over time. Following the implementation of the IAQCA, the proportion of regulated pollutants among the TVOC decreased, whereas that of unregulated pollutants increased. These findings indicate that IAQCA contributes to reducing the concentrations of indoor volatile pollutants in newly constructed apartments.