Background <p>Chronic gastritis is a common gastrointestinal disorder and a potential precursor to gastric cancer. Although environmental factors have been associated with its occurrence, the combined relationships of soil characteristics and demographic variables with its spatial distribution remain unclear. This study aims to quantify associations between soil properties and the spatial distribution of chronic gastritis after accounting for population structure and spatial dependence.</p> Methods <p>Based on 15,836 chronic gastritis cases from 2021 to 2023 in Yanshan County, we explored the disease’s spatial characteristics and its links to soil and demographic factors. GeoDetector was used to quantify factor explanatory power and interactions, supported by sensitivity analyses of spatial scales and data sources. Additionally, Generalized Additive Models (GAMs) were constructed to identify nonlinear relationships. By combining point-level risk estimation with grid-based aggregation (square and hexagonal), the study effectively addressed the Modifiable Areal Unit Problem (MAUP) while controlling for potential environmental and socioeconomic confounders.</p> Results <p>The spatial distribution of chronic gastritis exhibited significant geographic clustering, primarily centered in urbanized areas, with notable age-related heterogeneity. Individuals aged 65 and above showed the highest relative risk, with high-risk clusters concentrated along the county’s eastern boundary. GeoDetector and GAM analyses revealed that soil organic carbon, pH, soil type, and texture were key drivers of spatial variation. Notably, interaction effects—particularly between soil type and texture or age—enhanced the explanatory power for disease risk. GAM further identified nonlinear associations between soil properties and disease occurrence, suggesting complex ecological pathways.</p> Conclusions <p>This study demonstrates that chronic gastritis risk in Yanshan County is shaped by complex interdependencies between demographic characteristics (primarily age) and soil environmental factors. The findings highlight the significant role of soil physicochemical properties and their interactive effects in disease spatial epidemiology. These results provide a scientific basis for identifying geographic hotspots and high-risk populations, emphasizing the necessity of integrating environmental management into targeted public health strategies and resource allocation for gastric disease prevention.</p>