Climate change threatens human health, and health care as an industry is responsible for a significant fraction of greenhouse gas (GHG) emissions. We examine the reduction in GHG emissions from transportation to outpatient clinic visits with the growth in telehealth services.

This is a retrospective review of outpatient care at a health system serving over 600,000 members. Using average distances, we calculate transportation-related GHG emissions for ambulatory visits. The ambulatory visit carbon intensity is the total GHG emissions normalized by number of patient visits annually.

From 2015 to 2020, total outpatient visits increased at 3.2% annually, to 2.7 million. Telehealth visits increased by an average of 53.2% annually while in-person visits saw modest gains of 1.5% annually until 2020, when they declined 46.2%. Transportation GHG emissions rose from 18.5 to 19.6 (in 2019) before declining to 10.5 kt CO2-eq in 2020. Ambulatory visit carbon intensity monotonically declined from 8 to 4 kg CO2-eq per visit.

Increasing telehealth use in an integrated health system in the Pacific northwest of the United States corresponded to a dramatic decrease in ambulatory visit carbon intensity.