All participating organizations will receive access to PeerOnCall, a mobile mental health and peer support platform co-designed by and for Canadian public safety providers (PSP) that includes: a) an app for frontline workers, b) an app for peer support providers, and c) an administrative portal for organizational leaders. The structured implementation (intervention) group will follow a structured protocol designed to promote weekly app engagement.

All participating organizations will receive access to PeerOnCall, a mobile mental health and peer support platform co-designed by and for Canadian public safety providers (PSP) that includes: a) an app for frontline workers, b) an app for peer support providers, and c) an administrative portal for organizational leaders. The standard implementation (control) group will receive baseline support, allowing firefighters to use the app as they choose.

The structured implementation (intervention) group will follow a structured protocol designed to promote weekly app engagement. This includes regular updates to customized content, reminders to use the app, and feedback on use. Weekly content updates and push notifications will be provided through the app, and the research team will communicate monthly with organizational champions with feedback reports on app utilization to reinforce engagement.

Impact on mental health (primary) outcome - A 10-point visual analogue scale (VAS) will be used to measure mental health status as a continuous variable, aligning with the mental health continuum commonly used in the public safety community. The scale uses color coding from 0 (green/well) to 10 (red/crisis) with strong concurrent validity (r = .60 to .74) compared to other anxiety measures. Pilot research indicated that firefighters are resistant to lengthy psychological questionnaires, so this brief, intuitive, and widely accepted single-item scale was selected to optimize response rates. App users will receive monthly in-app notifications prompting them to complete the scale. Since the scale is integrated into the app, data can be directly linked to app utilization.

App opens will be tracked as a binary variable, measuring whether an employee opens the app at least once during the 12-month study period. This initial adoption measure will be monitored using unique ID numbers to track the total number of app opens per user. A list of eligible employees will be established at the start of the intervention and monitored over time to assess engagement across the organization.

Peer support outreach will be measured by the number of text or phone interactions initiated with a peer support provider. Software analytics will track individual use patterns, including whether users reach out once or multiple times to peer support. Higher outreach frequency reflects greater engagement with the app.

The secondary outcome is firefighter work performance, measured using the 36-item Work Limitations Questionnaire for Firefighters (WLQ-F), which assesses physical, cognitive, social, emotional, and time-related work demands. Responses are scored on a 5-point Likert scale from 0% (not limited at all) to 100% (unable to do), with higher scores indicating greater limitations.