Public responses to health-oriented warning labels in car advertising: Implications for sustainable and active mobility

Private car use has significant implications for public health, contributing to air pollution, road traffic injuries, and physical inactivity. In this context, communication-based regulations that aim to reduce car dependency can support both environmental and health goals. This study evaluates the introduction of mandatory health and environmental warnings in car advertising as an emerging policy instrument to promote sustainable and healthy mobility, drawing on evidence from Granada (southern Spain). A qualitative design was employed, using focus group discussions with 37 adults private car users segmented by age and level of environmental concern. The study explored participants’ awareness of car-use warnings, their perceptions of message credibility, and the behavioural and cognitive responses these warnings elicited. Findings indicate that many participants overlooked or dismissed the warnings as symbolic, particularly when the messages were small, poorly integrated, or perceived as inconsistent with broader transport and health policies. Nevertheless, the warnings prompted moral reflection and cognitive engagement among younger and more environmentally concerned participants, suggesting their potential contribution to gradual cultural change in mobility attitudes. Policy coherence, visibility, and credibility are critical conditions for the success of communication-based interventions. When integrated into broader strategies that promote active and sustainable travel, warning labels can complement public health efforts to reduce emissions, sedentary lifestyles, and traffic injuries. The study offers practical insights for policymakers seeking to design credible, health-aligned information tools that foster behavioural change toward healthier and more sustainable mobility. • Examines mandatory health and environmental warnings in car advertising in Granada, southern Spain. • Explores public awareness and perceived credibility of car-use warnings. • Finds limited direct behavioural impact but notable symbolic and normative effects. • Highlights the role of warnings within broader public health and mobility strategies. • Provides policy-relevant insights linking transport regulation and health outcomes.