Air pollution remains a major challenge, especially in developing countries, requiring joint efforts from governments and society. This study examines how mass media, through its emotional tone, functions as an informal regulator of air pollution in China’s “war on air pollution”. Using daily data on media sentiment, air quality and related variables across Chinese cities, we find that negative emotional tones in environmental news are significantly associated with lower pollution levels. We identify mechanisms through which media influence public awareness, trigger government responses and pressure firms to reduce emissions. Our findings highlight the media’s role beyond information dissemination to shape agendas and social norms, even in contexts with restricted press freedom. This study offers new insights into how emotional framing in mass media contributes to environmental governance in developing countries.
