The quality and reliability of short videos about passive smoking on Bilibili and TikTok: A cross-sectional study.

INTRODUCTION: Passive smoking is associated with substantial morbidity and mortality, yet public awareness of its health risks remains limited. As social media increasingly serves as a source of health information, this study evaluated the quality and reliability of passive smoking-related short videos on two major Chinese platforms, Bilibili and Douyin (TikTok in China). METHODS: In this cross-sectional study, the top 100 videos for each Chinese search term ('passive smoking' and 'secondhand smoking') were retrieved from Bilibili and Douyin on 10 June 2026. After excluding duplicates, irrelevant videos, promotional videos, and videos shorter than 30 seconds, eligible videos were analyzed for basic characteristics and engagement metrics. Two independent reviewers assessed video quality using the Global Quality Scale (GQS), modified DISCERN (mDISCERN), Journal of the American Medical Association (JAMA) benchmark criteria, and Video Information and Quality Index (VIQI). Comparisons were performed using non-parametric tests, and correlations were examined using Spearman analyses. RESULTS: A total of 157 videos were included (59 Bilibili, 98 Douyin). Bilibili videos were significantly longer than Douyin videos (median: 130.0 vs 73.0 s, Z= -3.93, p<0.001), whereas Douyin videos received more comments (median: 89.0 vs 27.0, Z= -2.48, p<0.05) and shares (median: 1829.5 vs 72.0, Z= -4.88, p<0.001). Overall, video quality and reliability were moderate. No significant differences were observed between platforms in GQS, mDISCERN, or JAMA. However, Douyin videos achieved significantly higher VIQI scores than Bilibili videos (median: 12.0 vs 11.0, Z= -3.37, p<0.001). Videos produced by science communicators and doctors consistently demonstrated higher quality than those uploaded by lay users. Engagement metrics were not associated with video quality or reliability. CONCLUSIONS: Passive smoking-related videos on Douyin and Bilibili provide moderate-quality health information. Videos from science communicators and doctors were of higher quality than those from lay users. Video popularity does not reflect information reliability.