Influence Mechanisms of Multidimensional Risk Communication Strategies on Public Altruistic Protective Behavior: Evidence from Public Health Emergencies

Background Altruistic protective behavior is pivotal to community resilience during public health emergencies, yet prior research has rarely integrated how multidimensional risk communication strategies shape such behavior. Drawing on the protective action decision model and risk communication theory, we examine how information sources, communication content, narrative style, and communication media influence public altruistic protective behavior through risk perception, and whether trust in authoritative information sources conditions these effects. Methods We conducted a cross-sectional online survey in mainland China (October–December 2023) using stratified site selection across 11 provincial-level regions. After data cleaning, 1,417 valid responses were retained. Validated multi-item scales were adapted to the Chinese context. Analyses included hierarchical ordinary least squares regressions, mediation tests with bias-corrected bootstrapping (PROCESS Model 4; 5,000 resamples), and moderation tests (PROCESS Model 1; 5,000 resamples). Multicollinearity and common-method bias were assessed (VIFs < 5; Harman single-factor test). Results Each communication dimension—information sources, communication content, narrative style, and communication media—was positively associated with altruistic protective behavior,albeit with heterogeneous effect sizes across dimensions. Risk perception exerted a significant positive mediating effect between risk communication and public altruistic protective behavior. Trust in authoritative information sources negatively moderated the path from information sources to risk perception, indicating a “high-trust attenuation” pattern whereby strong trust in authoritative sources reduces the incremental impact of non-authoritative sources on perceived risk. Conclusions Findings extend PADM to the collective-action domain by specifying how multidimensional risk communication promotes altruistic protection via risk perception and how trust calibrates source effects. Practice implications include building coordinated, multi-source messaging matrices; tailoring high-precision content to audience segments; combining story-based and data-based narratives; and orchestrating cross-media delivery.