During 2013–2014, China launched a nationwide, real-time air quality monitoring and disclosure programme which substantially expanded public access to pollution information. This column analyses the impact of the programme and finds that it triggered a cascade of changes in household behaviour, prompting people to find out more online about pollution-related topics, adjust their day-to-day consumption to avoid exposure to pollution, and exhibit a higher willingness to pay for housing in less-polluted areas. The programme’s estimated annual health benefits far outweigh the combined costs of the programme and associated pollution-avoidance behaviours.