National healthcare services significantly contribute to ambient air pollution and greenhouse gases, particularly through transport and energy generation. Hospitals bring together vulnerable patients in high-traffic settings often in urban areas where there are significant baseline concentrations of ambient pollutants. Therefore, there is a requirement for hospitals to look at ways of reducing their emissions of airborne pollutants, ideally within the framework of achieving net zero goals. This study details the initial implementation of the UK's Clean Air Hospital Framework (CAHF) at two major UK hospitals. CAHF is a proactive self-assessment tool designed to reduce the generation of air pollution from hospital activities. It comprises 215 compliance actions across seven key categories: travel, procurement, design & construction, energy generation, communication & training, outreach & leadership and local air quality. CAHF implementation has focused on sustainable travel options, parking policy, energy efficiency improvements, staff training, education, the adoption of green procurement policies and the incorporation of sustainable travel considerations into new infrastructure designs. Currently, the hospitals are more than half-way towards achieving their implementation goal. To monitor the future overall effectiveness of CAHF, a network of 32 NO2 diffusion tubes was set up across the hospital sites, together with continuous monitors for NO2, PM10 and PM2.5 measurement, and four indoor particulate matter monitors at each hospital. The monitoring programme was supplemented with the development of an ADMS-Urban dispersion model for the site, focussing on emissions from significant adjacent road networks. This study provides an evidence-based exemplar for the CAHF approach and provides a blueprint to support other hospitals to engage in this process.