This is an interventional study (quasi-experimental) without a control group, conducted in a hospital surgical unit to improve the waste segregation process during surgical procedures. The study was carried out between May 2023 and 2024 in a Catalan University Hospital with 380 beds, a surgical unit with 16 operating rooms, 320 professionals, and a total of 27,990 surgical procedures performed in 2023.

The study was structured into three phases: Phase 1: Baseline assessment of professionals' perceptions of recycling and measurement of plastic and cardboard recycling levels during surgical procedures. Phase 2: A motivational intervention was conducted for all surgical unit professionals, and the segregation process was progressively implemented. Phase 3: Full implementation of the recycling circuit.

The interventional study is based on the socio-ecological model (Sallis JF et al., 2006) (10.1146/annurev.publhealth.27.021405.102100).

The independent variable in this study is the multilevel program aimed at improving segregation during the surgical process. Data collection was conducted according to each phase of the study using questionnaires addressed to professionals, checklists during the perioperative process, and measurements of the volume of material segregation by type (plastic, paper, etc.). The carbon footprint and waste segregation volume were calculated throughout all phases.

Before implementing the motivational intervention for professionals, an ad hoc questionnaire was administered to assess their motivation for waste segregation in the workplace. The questionnaire comprised seven questions, with professional category as the only sociodemographic data collected. The remaining questions used a numerical rating scale from 0 to 10 to evaluate respondents' level of concern and engagement in recycling in their personal lives, as well as their interest in adopting recycling practices in their work environment.

Follow-up questionnaires were administered throughout the implementation process to gather perceptions regarding the segregation process. The final questionnaire also assessed overall satisfaction with the implemented recycling program and the perceived need for its implementation in other hospitals.

To quantify the degree of segregation, the number of bags, kilograms per day, and kilograms per week were calculated for each type of material.