A year-long field study of eight roadside gardens in London found that hedges and plentiful planting gave the lowest particle pollution, while paved gardens were the hottest and most polluted.
A year-long field study in two London neighbourhoods has found that front gardens can act as a first line of defence against air pollution, The Guardian reported on Oct. 30. Researchers measured pollution in eight gardens beside busy roads, one set about 10 metres from the North Circular and another about 15 metres from a busy road in east London. Gardens with hedges and plentiful vegetation had the lowest particle pollution, and the best-performing garden had up to 80% less than paved gardens. Gardens with lawns also showed stable, consistently low levels.
Paved gardens recorded the highest temperatures as well as the highest pollution, and in summer could be up to 6C hotter than richly planted ones. Prof Prashant Kumar of the University of Surrey, who coordinated the study, said the cooling effect is especially clear and could matter on hot nights. The researchers explained that hedges, shrubs and trees alter how traffic pollution flows, with leaves trapping particles and absorbing gases. The protection is more limited in spring, when agricultural pollution can spread across wide areas.
Gardens cover about 41% of Greater London, compared with 27% of Cardiff and 23% of Edinburgh, according to the report. Dr Karina Corada-Pérez of the University of East London, the first author, said the pressure to pave front gardens is real, citing low-maintenance needs and off-street parking. Her message was to keep gardens green wherever possible, and she called for guidance and incentives that balance parking, accessibility and maintenance with the health, climate and environmental benefits of greener front gardens. The findings come from eight gardens, so they are a first-of-its-kind indication rather than a universal rule.
