In order to monitor and reduce the spread of respiratory diseases in urban settings, this paper examines the Smart4COV19 project, an international consortium spanning Bulgaria, Indonesia, and Vietnam that creates a Resilience City framework by combining Earth Observation (EO) assets with in situ health data. In addition to data from official monitoring stations and low-cost sensor networks, the project tracks NO₂, CO, and the Absorbing Aerosol Index (AAI) as a proxy for particulate matter using Sentinel-5P TROPOMI and MetOp GOME-2 instruments from the EU Copernicus program. The composite Pollution Index (PI), which was developed using quartile classification and GIS-based spatial aggregation, is a noteworthy innovation. Compared to single-pollutant measures, it shows a substantially higher spatial relationship with COVID-19 incidence across 28 Bulgarian towns. In Sofia and Surabaya, 3D urban modeling based on LiDAR and GNSS further integrates environmental risk data with hospital capacity and medical waste logistics. The results provide a scalable framework for handling respiratory health emergencies in both temperate and tropical regions and validate the usefulness of open-access Copernicus services for urban health surveillance.