Personal traits as the core determinant of human heat tolerance: a multi-factorial interaction analysis based on the health ecological model

With the increasing frequency of human heat exposure events driven by global climate warming, this study employed the health ecological model to systematically investigate the influencing factors of heat tolerance and their interaction pathways and mechanisms across multiple dimensions including personal traits, behavioral characteristics, environmental adaptation behaviors, and interpersonal networks, aiming to address the risk of heat injury in high-temperature environments.

A cross-sectional survey was conducted on 2596 university faculty and students in Chongqing from August 21 to September 13, 2024, via the Wenjuanxing and WeChat platforms. Based on the survey data, heat tolerance was classified into 3 levels (low, moderate, strong). Chi-square test, multinomial logistic regression, and structural equation modeling were applied to analyze group differences, independent effects, and path relationships of demographic characteristics and factors at each level of the health ecological model on heat tolerance.

Heat tolerance exhibited group differences with sociodemographic characteristics (sex, age, heatwave experience), personal traits, behavioral characteristics, environmental adaptation behaviors (shower frequency, wearing hats outdoors), and interpersonal networks (weather monitoring, timely seeking help for heatstroke) (P<0. 05). Specifically, females demonstrated significantly lower probabilities of achieving moderate heat tolerance (OR=0. 496, 95%CI: 0. 390 to 0. 631) and strong heat tolerance (OR=0. 250, 95%CI: 0. 178 to 0. 349) compared to males (P<0. 001). The participants aged 16 to 18 years (OR=3. 778, 95%CI: 2. 028 to 7. 039) and 19 to 21 years (OR=1. 913, 95%CI: 1. 021 to 3. 586) were more likely to attain strong heat tolerance than those aged ≥26 years (P<0. 05), and those without heatwave experience showed significantly reduced probability of achieving strong heat tolerance (OR=0. 475, 95%CI: 0. 257 to 0. 878, P<0. 05). Structural equation modeling further revealed the multipath interactions among these factors. The male advantage in heat tolerance was manifested not only through direct physiological effects (standardized path coefficient=0. 261) but also indirectly via enhancement of personal traits (standardized path coefficient=0. 185). Although increasing age exerted a direct negative effect on heat tolerance (standardized path coefficient=-0. 067), its promotion of personal traits (standardized path coefficient=0. 038) indirectly offset this adverse effect. Personal traits emerged as the core determinant of heat tolerance, with a standardized path coefficient as high as 0. 696, substantially exceeding all other factors, and serving as a critical mediating variable regulating the overall effects of sex, age, and behavioral characteristics on heat tolerance. Furthermore, although behavioral characteristics showed no significant direct effect on heat tolerance (P=0. 871), they generated significant indirect effects through strengthening personal traits (standardized path coefficient=0. 304), whereas environmental adaptation behaviors demonstrated a negative impact (standardized path coefficient=-0. 143), suggesting that over-reliance on environmental adaptation may suppress the expression of heat tolerance.

Heat tolerance is influenced by multiple integrated factors, among which personal traits constitute the core determinant exerting significant direct and indirect effects on heat tolerance. Enhancing personal traits represents the key strategy for improving heat tolerance and reducing the risk of heat injury.