Urban form and air pollution: Clustering patterns of urban form factors related to particulate matter in Seoul, Korea

Despite the aggressive emission control efforts in Korea over the past decades, surface-level particulate matter (PM) concentrations have increased in Seoul since 2012. What remains unknown are the influences of urban form and their interactions with seasonal and cyclic changes. This study investigates the diurnal pattern of PM concentrations (PM2.5 and PM10) and their clustering patterns related to urban form factors in Seoul, Korea. Using data obtained from 802 environmental sensors distributed across the city from April 2020 to March 2021, we found the highest PM concentrations in high traffic-concentrated areas with high-rise buildings as well as areas characterized by high proximity to highways and high mixed land uses. Furthermore, diurnal differences in pollutant concentrations were more pronounced in high traffic-concentrated areas with high-rise buildings as opposed to the areas characterized by a larger fraction of residential apartment complexes. This study demonstrates that high-resolution environmental sensor data can provide more granular information regarding spatial distribution and diurnal patterns of PM, which can help inform more targeted intervention strategies. The findings also suggest that bundling of urban design strategies aimed at reducing traffic emissions while diluting traffic pollutants through dispersion could be effective in managing urban air quality problems in high-density cities.