[Knowledge, attitude and practice about first aid and influencing factors in key populations in Beijing: a large cross-sectional study].

To investigate the status of knowledge, attitude and practice about first aid and influencing factors in key population, those who have frequent contacts with people and might be "first aid" promoter in general population of Beijing, and provide evidences for the promotion of first aid. This study was a cross-sectional survey based on the "Emergency Rescue Capacity Training Project". Using cluster sampling, we recruited 9 591 participants after the training in Beijing for survey with a self-designed questionnaire from October 2021 to March 2022.