Carbon Emissions From Patient Travel for Health Care.

Importance: The US health care sector accounts for about 8.5% of national greenhouse gas (GHG) emissions. Reliable estimates of emissions associated with health care-related travel are essential for informing policy changes.

Objective: To generate a comprehensive national estimate of carbon emissions due to patient health care-related travel in the US.

Design, Setting, And Participants: This cross-sectional study used data from the 2022 National Household Travel Survey (NHTS), conducted from January 2022 to January 2023. Participants were selected using an address-based sample from the US Postal Service Delivery Sequence File. Participating households reported all trips taken within 24 hours by all household members aged 5 years or older. Approximate emissions per mile were obtained from typical vehicle emissions data provided by US government institutions. Data were analyzed between March 11 and May 29, 2024.

Main Outcomes And Measures: Estimated annual CO2 equivalent (CO2e) emissions from patient health care-related travel per year, per patient, per trip, and per mile. A survey-weighted λ regression analysis was used to identify factors associated with higher CO2e emissions per trip. An alternative scenario analysis estimated reductions if 30% or 50% of private vehicle users switched to electric vehicles.

Results: The sample included 16 997 participants with a weighted total of 3 506 325 536 US health care trips. Of these trips, 52.0% were reported by female travelers, 80.1% were made in urban areas, and 19.9% were made in rural areas. These trips accounted for 84 057 963 340 miles, resulting in weighted annual estimated emissions of 35.7 megatons (Mt) (95% CI, 27.5-43.9 Mt) CO2e. Each mile traveled generated an estimated 424 g (95% CI, 418-428 g) CO2e. Emissions per trip were higher (exponentiated coefficient [exp(β)], 2.19; 95% CI, 1.51-2.86; P < .001) for rural patients compared with urban patients. However, 69.3% of emissions were attributable to urban patients and 30.7% to rural patients. Patients with annual median household incomes of $50 000 to $99 999 generated higher trip emissions (exp[β], 1.92; 95% CI, 1.09-2.76; P = .003) compared with those with incomes of $25 000 or less. A 30% shift to electric vehicles was estimated to reduce health care-related carbon emissions to 27.6 Mt (95% CI, 20.7-34.6 Mt) CO2e, and a 50% shift was estimated to lower emissions to 22.3 Mt (95% CI, 16.0-28.6 Mt) CO2e.

Conclusions And Relevance: This cross-sectional study estimated that annual patient health care-related travel in the US generated 35.7 Mt CO2e, which accounts for a small but important proportion of total health care-related emissions in the US. These findings are essential for informing health care policy decisions and suggest that strategies such as telehealth and the adoption of electric vehicles may contribute to a small but significant reduction in health care-related GHG emissions.