Spatial Co-Variability of Atmospheric Pollution and COVID-19 Incidence

This study examines the spatial co‑variability between atmospheric pollution and cumulative COVID‑19 incidence across Bulgaria’s 28 regions during 2020–2024. Satellite observations from GOME‑2 (AAI) and Sentinel‑5P TROPOMI (NO₂), combined with ground‑based air‑quality measurements, were aggregated into long‑term regional indicators. Because “neither AAI nor NO₂ alone reproduces the spatial pattern of COVID‑19 incidence”, the analysis introduces a normalized, quartile‑based Combined Pollution Index integrating both pollutants. The resulting index shows a “striking spatial correspondence with COVID‑19 distribution”, substantially outperforming individual pollutant metrics. Rank‑based statistical tests (Spearman and Kruskal–Wallis) confirm a significant positive association between pollution burden and disease incidence. While the study does not infer causality, it demonstrates the value of Earth Observation and GIS integration for environmental‑health surveillance and future epidemiological research.