Nationwide analysis of the association between nature park visits and adult asthma risk in urbanized neighborhoods

Evidence linking greenspace to asthma remains mixed, largely because prior studies infer exposure from static land-cover maps rather than where people actually spend time. Here, we bridge that gap, conducting the first nationwide analysis to translate passively collected GPS traces into an “actual-use” nature park metric. This study used millions of visit records to 127,752 nature parks across the contiguous United States based on a large-scale dataset from GPS-enabled mobile devices to investigate the associations between nature park visits and adult asthma risk at the neighborhood level in urbanized areas. The exposure-response relationship derived from XGBoost-SHAP analysis shows that increasing park visits reduces asthma risk, but the protective effect plateaus when visits exceed 51.94 per year. Stratified by park visits, the second, third, and fourth quartiles of nature park visits were associated with a reduction in high asthma risk by 29 % (OR: 0.71, 95 % CI: 0.67–0.75), 46 % (OR: 0.54, 95 % CI: 0.51–0.57), and 65 % (OR: 0.35, 95 % CI: 0.33–0.37), respectively, compared to the first quartile. We further observed significant additive interactions between nature park visits and environmental factors on asthma risk, with high NDVI (Normalized Difference Vegetation Index) reducing asthma risk (AP = −0.1, 95 % CI: −0.19 to −0.01), while high urban heat island index (UHI) (AP = 0.56, 95 % CI: 0.49 to 0.64) and high PM2.5 levels (AP = 0.24, 95 % CI: 0.15 to 0.32) increased asthma risk. These findings highlight the importance of mobility-informed measures of nature park use, identify non-linear saturation effects, and demonstrate interactions with urban environmental stressors. Policymakers and urban planners should integrate human mobility patterns, environmental contexts, and equity considerations into greenspace strategies to effectively mitigate asthma risk and enhance respiratory health in urban settings.