Inter-Site Correlation of Ambient Air Pollutants Across Swiss Plateau NABEL Stations (2015–2019)

This dataset presents inter-site Spearman correlation matrices for six ambient air pollutants—PM₁₀, PM₂.₅, elemental carbon (EC), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and carbon monoxide (CO)—recorded by the Swiss NABEL monitoring network between 2015 and 2019.The analysis focuses on NABEL stations located in the Swiss Plateau, excluding high-altitude and southern Alpine sites due to differing meteorological profiles and lack of relevance to the study population. Strong inter-site correlations across the Plateau support the use of regional data for exposure modeling.The Zurich–Kaserne monitoring station, located ~27 km from the study clinic in Pfäffikon SZ, was used as the primary reference site due to its continuous data coverage and proximity to the majority of patients. While PM₂.₅ data included some gaps, these were imputed using gradient-boosted regression based on co-monitored pollutants. Minimal missingness in the remaining pollutants was addressed by flagged linear interpolation.Two supplementary figures accompany this dataset:<b>Supplementary Figure 1</b> maps the included NABEL stations and highlights spatial coherence across the Swiss Plateau.<b>Supplementary Figure 2</b> shows the geographic distribution of patient residences by postcode (2015–2017), illustrating the cohort’s concentration in the Zurich Lake region and proximity to both the clinic and Zurich–Kaserne. While the time window slightly precedes the air pollution data, the residential pattern remained stable throughout the study period.This dataset supports environmental exposure modeling in studies linking regional air pollution to urinary metal excretion in outpatient populations.