The thermal sensory-risk gap in the old-old: age-stratified benchmarks for humid subtropical parks

Global warming and population aging pose increasing challenges to urban thermal perception for older adults. This study investigates age-related heterogeneity in thermal perception across three cohorts (60–69, 70–79 and $ \ge 80$ years) in Fuzhou, a representative humid-subtropical city in China. Field microclimatic monitoring and 557 questionnaire surveys were integrated to derive age-specific outdoor thermal benchmarks. A sensory-risk gap was identified in the $ \ge 80$ cohort. Their Thermal Comfort Range (TCR) upper bound increased to 36.65°C, while the 80% Thermal Acceptability Range (TAR) threshold declined to 39.55°C relative to the 70–79 cohort (39.87°C), indicating a narrowing physiological safety margin at advanced age. Confusion matrix analysis revealed a systematic underestimation of heat stress, with 24% of $ \ge 80$ participants reporting “neutral” under model-predicted “warm” conditions. Spatial analysis demonstrated that maintaining a Sky View Factor (SVF) below 0.15 consistently sustained Safe Zone conditions in urban parks. These findings challenge sensation-based planning paradigms and support physiology-calibrated thermal risk governance strategies to enhance climate resilience in aging societies.