Electronic Cigarettes as a Harm Reduction Strategy Among People With Opioid Use Disorder on Buprenorphine

Inclusion Criteria * Age ≥21 years * Smoke ≥5 CPD for ≥1 year * Daily CC smoker * Willing to switch to EC * Exhaled CO ≥6 ppm * Diagnosed with OUD * Stable on bupropion treatment * In good physical and mental health * Able to use a smartphone * Willing to participate in all study components * Able to provide informed consent Exclusion Criteria * Interested in quitting CC (contemplation stage of change) * Use of EC on ≥4 of the past 30 days * Use of other tobacco products (e.g., cigars, smokeless tobacco) on ≥9 days of the past 30 days * Use of nicotine replacement therapy, smoking cessation medication, or a cessation attempt in the past 30 days * Hypertension * Medical condition that would contraindicate participation * Meet DSM-V criteria for major depressive episode, psychotic episode, or manic episode * Current suicidal ideation or suicide attempt in the past year * Psychiatric hospitalization in the past year * Contemplating pregnancy, currently pregnant, or breastfeeding * Unable to speak and/or read English