ChiCTR‐TRC‐11001268.

Methods	Parallel randomised trial; Hong Kong, China
Participants	Study population: 900 Inclusion criteria: first responders, including fire fighters, police, ambulance officers, rescuers and auxiliary medical personnel with and without previous trauma exposure Exclusion criteria: individuals with psychiatric history or current diagnosis of psychiatric disorders will be screened out and referred for professional mental health services
Interventions	1. Psychological first aid. A model widely used and adopted as a community‐based intervention for reducing post‐disaster psychological distress in a form of 7 h of training delivered in 1 day 2. Wait‐list control
Outcomes	Primary outcomes: participants’ knowledge in disaster mental health, knowledge in PFA, self‐efficacy in delivering help in times of emergencies and actual helping behaviour Secondary outcomes: participants’ psychological well‐being, psychological distress and coping responses to stressful events and life satisfaction using a series of measurement tools including: GHQ‐28 (Chinese version), DASS‐21 (Chinese version), IES‐R, Brief COPE, Trauma History Questionnaire, MSPSS Data collection: baseline, 3‐ and 6‐month follow‐up
Notes	The trial is reported as completed, however we have only identified one published abstract. Further information sought from authors.