In this study, we investigated the spatiotemporal distribution and characteristics of air pollutants in Vientiane, Laos. Despite regulatory efforts, the city continues to face severe air quality issues, primarily due to the high concentrations of particulate matter (PM). Using both ground-based and mobile measurements, we determined that the major emission sources were roadside traffic, industrial activities, and night markets. The PM10 concentrations reached up to 1139 μg/m³ in night market areas, primarily due to outdoor grilling. Ground-based measurements were conducted using an optical particle counter (OPC), and mobile measurements were conducted using Sniffer4D sensors mounted on vehicles. Mobile measurements provided real-time data on air pollutant distribution, revealing several hotspots that are not covered by existing monitoring networks. The highest PM concentrations were found near congested roads, industrial areas, and night markets. Our findings highlight the inadequacy of the current air quality monitoring network and emphasize the need for its expansion, as well as specific regulations to target specific emission sources. This study highlights the importance of mobile air pollution monitoring using sensor technology, particularly the Sniffer4D system, which provides real-time, high-resolution data on PM distributions. By integrating this mobile sensing approach with stationary monitoring networks, we can achieve a more comprehensive understanding of air quality variations, addressing gaps in traditional monitoring methods.