Background: Nicotine contained in tobacco is highly addictive and tobacco use is a major risk factor for cardiovascular and respiratory diseases. Every year, more than 8 million people die from tobacco use.

Smoking-related mortality is significantly higher in people with serious mental illness. Is estimated that half of all deaths among individuals with mental illnesses are attributable to tobacco use. People with serious mental illness have greater daily tobacco consumption, nicotine dependence, and smoking relapse. While significant progress has been made in reducing tobacco use within the general population, rates of tobacco use remain high among individuals with mental illness. Smoking cessation often requires numerous attempts by these people. Thus, smokers with mental health illnesses may find it more difficult to quit, although highly motivated to quit.

Smoking cessation during hospitalization (total or partial) is cost-effective, as it reduces hospital readmissions, and mortality, and improves smokers' quality of life. Available quitting aids are both safe and effective in supporting cessation in tobacco users with mental illness and stopping smoking is associated with an improvement in mental health.

The investigators aimed to evaluate the feasibility and efficacy of adding an intensive smoking intervention to the usual treatment for patients with psychiatric disorders attending a day hospital of a tertiary hospital.

The investigators will perform a quasi-experimental, longitudinal, and prospective study in the mental health day hospital of the Hospital Clinic of Barcelona.

Adults attending the day hospital and willing to participate, under informed consent, will be invited to participate. Consecutive eligible individuals will be recruited and will be assigned to two groups, the control group, and the experimental group. Initially, patients will be recruited for the control group, once the control group is completed the experimental group will begin.

An assessment will be conducted at baseline (admission) and in the discharge. Sociodemographic and clinical data will be obtained.

Inclusion Criteria:

• Mental health day hospital inpatient.
• Smoker of at least 1 cigarette per day, electronic cigarette, or heated tobacco product daily for at least 1 month.
• Individuals who accept to participate in the study and give informed consent.

Exclusion Criteria:

• Cognitive impairment, dementia, or brain damage.
• Medically unstable.
• Explicitly demanding tobacco treatment.
• Trying to quit smoking using another intervention.
• Insufficient comprehension skills in Spanish or Catalan.