The playground of Goose Green Primary School in East Dulwich is full of activity: there’s a water area where children can create rushing rivers or meandering streams and a music station with percussion and wind instruments, as well as plenty of joyful running about for no apparent reason. But the playground is adjacent to a very busy road carrying 5 bus routes, a main route between Camberwell and the South Circular. It’s one of 1,148 schools in London within 150 metres of roads carrying 10,000 or more vehicles per day.

In 2017, David Jennings and Eleanor Margolies, members of Southwark Green Party, measured nitrogen dioxide levels outside the school as part of an area-wide study.