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 to 2023 and hospitalization records from 2008 to 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 1500 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.