S-DoT — Seoul's Citywide IoT Micro-Climate Sensor Network

Seoul's government wanted finer-grained, real-time environmental data than fixed national weather stations could provide, to understand how heat, air pollution and noise varied block-by-block across a city of nearly 10 million people, and to make that data usable for both policy and everyday citizen decisions.

Starting in 2019, the Seoul Metropolitan Government set out to build a citywide IoT sensor network capable of hyperlocal, high-frequency environmental monitoring and to open the resulting data to the public.

S-DoT (Smart Seoul Data of Things) became operational from April 2020 and grew to 1,100 IoT sensor stations sited across downtown areas (87%), mountains and parks (4%), and riversides (9%). Each station measures up to 17 variables — including temperature, humidity, illumination, noise, ultraviolet exposure, vibration, and PM10/PM2.5 particulate matter — every two minutes. A peer-reviewed 2023 study built a quality-management system to flag and correct faulty sensor readings across the network. From August 2021, Seoul opened the real-time data to the public through the Smart Seoul Map.

A citywide analysis of a full year of S-DoT data (April 2020–March 2021) found downtown areas ran 2.32°C warmer in summer and 2.16°C warmer in winter than mountain areas — a measured urban-heat-island effect. Seoul's government used this finding to recommend targeted measures for preventing heat-related crime and traffic accidents in city centres, and enhanced care protocols for vulnerable residents during hot summers.

S-DoT demonstrates strong technical scale, data quality (validated by independent peer-reviewed research) and public reach, and produced at least one concrete, quantified policy input (the heat-island finding), but no independent before/after evaluation of the resulting safety guidance's actual impact is documented.