Spatial Distribution of Long-Term Ultrafine Particle Concentrations and Systemic Lupus Erythematosus Burden in Central Mexico.

Long-term ultrafine particle (UFP) concentrations may reflect urban particulate pollution contexts relevant to autoimmune disease burden, yet evidence from middle-income countries remains limited. We characterized spatial patterns of municipal-level UFP concentrations and systemic lupus erythematosus (SLE) mortality and hospitalizations in central Mexico. SLE mortality records from 1998-2023 and hospitalization records from 2008-2024 were obtained from national health databases, and long-term UFP concentrations for 2010-2019 were estimated from satellite-based models. Municipal rate ratios, Jenks natural breaks, exploratory ecological analyses, and principal component analysis were used to describe spatial co-location patterns in selected municipalities. National SLE mortality rates ranged from 0.23 to 0.86 per 100,000 inhabitants, while long-term municipal mean UFP concentrations ranged approximately from 1,500 to 24,000 particles/cm³. Higher UFP concentrations and higher SLE hospitalization burden co-occurred in selected metropolitan municipalities, whereas SLE mortality patterns were more heterogeneous and should be interpreted descriptively. These ecological findings are hypothesis-generating and identify areas for future individual-level and multipollutant studies.