e13812 Background: Climate change is one of the grand challenges of the 21st century. The U.S. currently emits 11% of the annual global greenhouse gases, and 8-10% of its emissions result from the healthcare industry. Studies on the contribution of patients' commute for cancer treatment to healthcare-associated CO2 emissions remain limited. This study aims to determine the CO2 emissions of patients’ commute for cancer treatment among patients with malignancies at an urban safety net hospital. Methods: We conducted a retrospective study of patients seen at an oncology clinic from July 1, 2022 - June 30, 2023. Demographic data, data on visit diagnosis and indication (e.g., laboratory, infusion, or follow-up visits), and patients' home addresses were collected from the EMR. Distance between patients’ homes and the hospital was calculated using a Google Map API and a macro for distance. Total CO2 emissions from patients’ travel in miles were estimated at 400 grams of CO2 per mile based on the Environmental Protection Agency’s estimate of the average CO2 emissions for a passenger vehicle. The primary outcome was CO2 emissions from patients’ round-trip travel. The total estimated CO2 emissions were converted to equivalents of coal burned, smartphones charged, and gallons of gasoline used based on the EPA equivalencies calculator. Results: Of the 8,235 visits, 5,095 (61.8%) were follow-up/laboratory visits, and 3,137 (38.1%) were chemotherapy infusion visits. Of the 1,080 patients who attended the clinic, the mean age was 63.8 years, 700 (64.8%) were males, 379 (35.1%) were females, 525 (48.6%) were black or African American, 139 (12.9%) were whites. Breast cancer was the most common diagnosis, with 423 (39.2%) of patients. Each patient traveled an average of 9.6 miles round trip (Range = 0.7-298.6 miles) to receive cancer care. An estimated 1,520 grams of CO2 was emitted for each patient’s visit. A total of 79,582 round trip miles was made in 8,235 visits, which corresponds to 31,832 kg of CO2 emissions, equivalent to 35,658 pounds of coal burned, 1,462 propane cylinders used for a home, or 3,872,250 smartphones charged. Conclusions: Cancer care is associated with significant CO2 emissions. Efforts to decrease the overall carbon footprint of cancer treatment through adoption of telemedicine and alternative treatment schedules, are needed to reduce the effect of cancer treatment on the climate. [Table: see text]