About air quality in City of London
The City of London is the smallest local authority in the UK at one square mile, but its weekday daytime population — around 600,000 — makes air-quality exposure here disproportionately important. The principal hotspots are the Aldgate / Tower Hill gateway, the Beech Street tunnel under the Barbican, and the approaches to Tower Bridge and London Bridge. The City of London Corporation has historically been an early adopter of low-emission zone measures, and background NO₂ has fallen materially since the Tower Bridge low-emission-bus corridor and the City-wide 20mph rollout.
PM₂.₅ is dominated by regional inflows; on most days the City shares air with Westminster, Tower Hamlets, and Southwark. The borough has reasonable AQ monitoring density for its size, though the verdict reflects daytime ambient air and does not estimate worker- or resident-specific exposure.
Last reviewed: 2026-05-18