Conversations with our doctors frequently include ways that we can reduce health risks: eating better and taking more exercise, for instance. Air pollution is now a top five global risk factor for an early death. This has prompted an international group of cardiac organisations, societies and foundations to call for doctors to advise us on the air that we breathe. They want clinicians to become advocates for clean air and to address the impacts of their own facilities. The reason for this goes beyond the burden of disease from breathing poor air. It reflects the gains from improving it. Improvements in air pollution between 1999 and 2015 account for about 15% of the increased life expectancy for Americans. In 1962, debates on tobacco took an important step forward when UK doctors told people to stop smoking. In 2016 the Royal College of Physicians warned about the lifelong impacts of air pollution. Today, many hospitals are working to improve the air around their facilities and 10 hospitals will be measuring air pollution as part of the Breathe London project. It’s possible that soon, in towns and cities, doctors may suggest leaving cars at home to reduce air pollution, and instead advise people to walk along back streets or through parks away from busy traffic.