BackgroundHealthcare transportation, particularly the transportation of patients to access healthcare services, is a significant source of carbon emissions. This study aims to estimate the carbon emissions of patient transportation among patients receiving cancer care at an urban community safety net hospital. Materials and MethodsWe conducted a retrospective study of patients seen at the oncology clinic of an urban community safety net hospital between July 1, 2022, and June 30, 2023. Patients with at least one in-person visit in one year, documented home addresses, and oncologic diagnoses were included in the study. The distance between each patient's home address and the hospital was calculated using the Google Map API key and a macro to calculate distance in meters. The total estimated carbon emissions were calculated using the E.P.A. equivalencies calculator. The primary outcome was carbon emissions from patients' round-trip travel from home to hospital. ResultsFrom July 1, 2022, to June 30, 2023, 13,970 visits were made to the oncology clinic. Of these, 8,235 visits made by 1,080 patients met the criteria for inclusion in the final analysis. Of the 8,235 visits recorded, 5,095 (61.8%) were follow-up/laboratory visits. The 1080 patients who attended the clinic had a mean age of 63.8 years; 700 (64.8%) were males, and 525 (48.6%) were Black or African American. Breast cancer was the most common diagnosis, accounting for 423 (39.2%) of cancer diagnoses. Each patient traveled 4.8 (0.3-149.3) miles for a one-way trip and 9.6 (0.7-298.6) miles round trip to receive cancer care. Approximately 1,520 (280-119,440) grams of carbon were emitted per patient visit. A total of 79,582 round trip miles was calculated for the 8,235 visits made by all patients within one year, 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. ConclusionTravel to receive cancer care is associated with significant carbon emissions and poses a climate and public health risk. Efforts to decrease the overall carbon footprint of cancer treatment are needed to minimize the contributions of cancer treatment to climate change.