Environmental Toxicity of Driving Distance to External Beam Radiotherapy (EBRT) for Head and Neck Cancer Patients

Abstract

For many patients undergoing external beam radiotherapy (EBRT), distance from home to treatment center is significant and require housing in closer proximity to minimize this travel burden. Patient transport also contributes significantly to the carbon footprint of EBRT. We sought to define the difference of carbon dioxide (CO2) emissions from commuting for patients who stay at a charity housing (CH) facility during treatment for head and neck cancer (HNC) versus a commute from home. Patients with HNC were enrolled in an IRB-approved prospective protocol from 2019-2021. A distance of 3 miles (mi) was calculated from CH to our facility using Google Maps. Driving distance from home was indicated by patient self-report. Distance traveled per day Mon-Fri was doubled to account for driving to and from treatment. It was assumed that patients staying at CH returned home on weekends and that all used a standard, gasoline powered automobile for transportation to and from home. Transportation from CH to treatment was via a gasoline powered, 6-person shuttle. Both forms of transport were considered light-duty vehicles (LDV) with mileage and tailpipe emissions corresponding to the US on-road average (23.7 mi per gallon and 0.84 lb CO2/mi). For estimation of CH emissions, conversions were made from the reported electricity bill multiplied by the North Carolina grid emissions rate of 0.698 lb CO2/kWh. Natural gas used by CH for heating (prorated per patient) was estimated using the Piedmont Natural Gas rate (located in NC) and the monthly gas bill. Emissions from patient homes were assumed to be similar for patients commuting and making use of CH and therefore ignored. Forty-nine patients enrolled in the study: 38 drove themselves to treatment daily, and 2 stayed at CH. The remaining 9 patients indicated that they stayed with friends/family or in a hotel where travel distance to DCI was unknown. CH electricity emissions were estimated to be 8,823 lb CO2/month. CH gas emissions were estimated to be 2,210.6 lb CO2/month. Emissions at CH were calculated as 137.9 lb CO2 per patient per month. The median emissions of those who drove daily per course of EBRT was 1205.4 lb CO2 (IQR 366.0 - 2221.2). For the 2 patients who stayed at the CH, total mi per course were 650 and 774. Including emissions of CH, emissions per patient were 1305.6 and 1523.2 lb CO2. If these patients were to have driven daily from their home, emissions would have been doubled (2368.8 and 2646 lb CO2, respectively). CH was estimated to result in fewer emissions for those that live ≥ 12 miles from the treatment facility. Affordable and safe housing, such as charity housing is not only convenient for patients, but also reduces the environmental impact of travel for care for HNC. Patients who stayed at the charity housing in this study reduced their emissions from travel by nearly a half compared to driving daily in a personal vehicle. Further studies are imperative to continue to measure and mitigate the environmental toxicity of cancer care.