The role of oxygen in shelter-based overdose response: A qualitative needs assessment across shelter sites in Toronto, Canada

BACKGROUND: The toxic drug crisis in Canada is increasingly shaped by a complex and unpredictable unregulated drug supply characterized by polysubstance toxicity, including combinations of opioids and sedating agents that can produce prolonged respiratory depression not fully reversed by naloxone alone. Concurrent reductions in harm reduction infrastructure in Ontario, including the closure of supervised consumption services, may be shifting overdose burden into shelter settings, where overdose response capacity often remains limited and inconsistent. In this context, there is growing interest in whether oxygen and supportive respiratory care may strengthen overdose response within shelter environments. METHODS: We conducted a multi-site qualitative needs assessment across eight shelter sites in Toronto, Ontario. Semi-structured interviews were conducted with shelter staff (n = 17) and clients (n= 17) to examine overdose response practices, perceptions of oxygen use, and barriers and facilitators to implementation of oxygen-based medical directives. Data were analyzed using reflexive thematic analysis. RESULTS: Three themes were identified: (1) oxygen was perceived as a clinically valuable and client-centred intervention, particularly in the context of polysubstance overdoses where naloxone alone may be insufficient; (2) access to oxygen and pulse oximetry supported more structured, consistent, and confident response practices; and (3) training was identified as a critical enabler of effective implementation of oxygen. Participants described oxygen as improving clinical stabilization while also reducing distress associated with abrupt naloxone reversal and supporting more relationally responsive overdose care. CONCLUSION: Integrating oxygen into shelter-based overdose response may represent a feasible and pragmatic opportunity to strengthen overdose response capacity in high-risk environments. Expanding access to oxygen alongside standardized training, implementation supports, and clear clinical guidance may improve the consistency, equity, and quality of overdose response in shelter-settings.