With global warming intensifying, GI endoscopy is among the top three greenhouse gas-emitting medical procedures. Colonoscopy, a cornerstone for colorectal cancer (CRC) screening, significantly contributes to the carbon footprint (CF). This study quantifies CO₂ emissions in different steps of colonoscopy and evaluates the environmental impact of common polypectomy techniques to establish baseline CF data and identify opportunities for mitigation. This study included patients undergoing colonoscopy for CRC screening. CO₂ emissions were comprehensively measured at each step of the procedure (pre-, during, and post-colonoscopy), including energy consumption, all equipment and medications, waste management, and endoscopy reprocessing. Emission data were also collected for common polypectomy techniques, including cold forceps biopsy (CFB), cold snare polypectomy (CSP), hot snare polypectomy (HSP), and hot snare endoscopic mucosal resection (EMR), all performed according to standard polypectomy protocols.

Global warming refers to the long-term increase in Earth's average surface temperature, primarily caused by the buildup of greenhouse gases in the atmosphere due to human activities. The carbon footprint of a colonoscopy refers to the total greenhouse gas emissions (primarily CO₂ equivalents) generated throughout the procedure. While colonoscopy for colon cancer screening improves survival outcomes, it still contributes to environmental impact through energy use, medical supplies, and waste. Calculating a carbon footprint involves estimating the total greenhouse gas emissions, usually expressed in carbon dioxide equivalents (CO₂e).

Main formula : Carbon footprint (CO₂e) = Activity Data × Emission Factor

Carbon footprint assessment is a tool for assessing the magnitude of greenhouse gas emissions from public health care processes for planning, developing and systematically improving public health systems to reduce carbon footprints leading to environmental sustainability.

Carbon footprint measurement in this study

1. Volunteers underwent bowel preparation by taking laxatives until their stool appearance met the clear criteria. The amount of laxative taken was recorded.
2. A nurse conducted a medical history interview using a standardized safety checklist before the colonoscopy, measured the patient's vital signs, and established intravenous access for administering medication or fluids.
3. Research participants were fitted with a nasal oxygen delivery device and given intravenous sedatives to induce an appropriate level of sedation. Vital signs and fingertip oxygen saturation levels were monitored before starting the colonoscopy.
4. During the colonoscopy, the nurse monitored vital signs and oxygen saturation periodically and adjusted the sedative dosage based on the patient's level of consciousness.
5. Patients underwent colonoscopy for colorectal cancer screening and diagnosis. If a colonic polyp was found, it was removed according to clinical indications and current treatment guidelines. The size of the polyp was estimated visually by comparing it with the size of the resection instrument. In the event of bleeding or perforation, endoscopic procedures were performed as indicated for treatment. During the procedure, all equipment used, the volume of water, the type and amount of sedative medication, and the duration of the colonoscopy and colonic polypectomy were recorded for subsequent carbon footprint analysis.
6. The removed colonic polyp tissue was preserved in a formalin-containing specimen jar for pathological examination by a pathologist.
7. After the colonoscopy, the patient was transferred to a recovery room, where vital signs were monitored periodically until the participant regained full consciousness.
8. After polypectomy, the patient resumed antiplatelet and anticoagulant medications according to the timing recommended by standard clinical guidelines.

The data from the patient's intake of laxatives for bowel preparation through to the completion of the colonoscope cleaning process was recorded and analyzed to calculate the carbon footprint in collaboration with the faculty team from the Environmental Research Institute of Chulalongkorn University.

Inclusion Criteria:

• Patients aged 18-80 years

Exclusion Criteria:

• Patient status grade III-V according to the American Society of Anesthesiologists (ASA)
• Poor bowel preparation (grade <6 in the Boston Bowel Preparation Scale [BBPS])
• Endoscopic JNET type III or suspicion of malignancy
• Hematologic or coagulation disorders, Plt<140,000/mcL, INR>1.5
• anti-platelet/anticoagulant medication that could not be paused as recommended in the current guideline
• Emergency colonoscopy, GI bleeding, unstable vital sign, critical ill patient
• Inflammatory bowel disease
• Pregnancy
• Severe cardiopulmonary disease
• Severe infection
• Malignancy
• History of allergy to IV sedative medication

Patients aged 18-80 years who received a colonoscopy at King Chulalongkorn Memorial Hospital