The study explores the rise of fentanyl smoking culture in San Francisco, a significant shift from the traditional fentanyl injection. The research, conducted through rapid ethnography, involved semi-structured interviews with 34 participants from syringe service programs and video-recorded smoking sequences. Key findings include: 1. **Motivations for Transitioning to Smoking**: Participants cited difficulty injecting and fear of overdose as primary motivations for transitioning to smoking. Fentanyl's low cost ($10/gram) and variable quality further influenced this shift. 2. **Smoking Techniques and Materials**: Foil was the most common smoking material, but glass bubbles, bongs, and dabbing devices were also popular. Participants developed techniques to gauge potency and regulate dosage, with some consuming up to 50 mg of pure fentanyl daily. 3. **Social Aspects and Overdose Risks**: Smoking fentanyl is highly social, with participants sharing equipment, drugs, and information. However, concerns about hygiene and overdose risk to others were raised, particularly regarding the accumulation of fentanyl 'residue' on smoking materials. 4. **Overdose Risks and Residue**: The accumulation of fentanyl residue on smoking equipment poses a new overdose risk, as the potency of the residual drug can vary significantly between users. Participants often shared or traded this residue, leading to potential mismatches in tolerance. 5. **Harm Reduction and Education**: The study highlights the need for harm reduction education and culturally attuned interventions to address the risks associated with fentanyl smoking, including the sharing of equipment and the potential for high daily consumption rates. The findings underscore the importance of understanding the social and cultural dynamics surrounding fentanyl smoking to develop effective harm reduction strategies.The study explores the rise of fentanyl smoking culture in San Francisco, a significant shift from the traditional fentanyl injection. The research, conducted through rapid ethnography, involved semi-structured interviews with 34 participants from syringe service programs and video-recorded smoking sequences. Key findings include: 1. **Motivations for Transitioning to Smoking**: Participants cited difficulty injecting and fear of overdose as primary motivations for transitioning to smoking. Fentanyl's low cost ($10/gram) and variable quality further influenced this shift. 2. **Smoking Techniques and Materials**: Foil was the most common smoking material, but glass bubbles, bongs, and dabbing devices were also popular. Participants developed techniques to gauge potency and regulate dosage, with some consuming up to 50 mg of pure fentanyl daily. 3. **Social Aspects and Overdose Risks**: Smoking fentanyl is highly social, with participants sharing equipment, drugs, and information. However, concerns about hygiene and overdose risk to others were raised, particularly regarding the accumulation of fentanyl 'residue' on smoking materials. 4. **Overdose Risks and Residue**: The accumulation of fentanyl residue on smoking equipment poses a new overdose risk, as the potency of the residual drug can vary significantly between users. Participants often shared or traded this residue, leading to potential mismatches in tolerance. 5. **Harm Reduction and Education**: The study highlights the need for harm reduction education and culturally attuned interventions to address the risks associated with fentanyl smoking, including the sharing of equipment and the potential for high daily consumption rates. The findings underscore the importance of understanding the social and cultural dynamics surrounding fentanyl smoking to develop effective harm reduction strategies.