OBJECTIVE: Health services contribute significantly to carbon dioxide (CO(2)) emissions and, while services in the UK are beginning to address this, the focus has been on reducing energy consumption rather than road transport, a major component of emissions. We aimed to compare the distances travelled by patients attending mobile breast screening clinics compared to the distance they would need to travel if screening services were centralized. METHODS: Anonymized postcode records were analysed to determine driving distances potentially saved through attendance at 20 mobile breast screening clinics rather than at two centralized locations. Based on assumptions for the typical car used, the CO(2) emissions were calculated for the current case of decentralized service through mobile clinics compared to a hypothetical case where only centralized services are available over one complete three-year cycle of breast screening invitations. RESULTS: The availability of mobile breast screening clinics for the 60,675 women who underwent screening over a three-year cycle led to a return journey distance savings of 1,429,908 km. Taking into account the CO(2) emissions of the tractor unit used for moving the mobile clinics around, this equates to approximately 75 tonnes of CO(2) saved in any one year. CONCLUSIONS: Decentralizing health care delivery can potentially provide substantial reductions in emissions at the same time as improving the patient experience. Thus, the 'care close to home' agenda can simultaneously improve health outcomes and the environment.