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    Person monitoring air quality
    ​Calibration of air quality monitoring equipment
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    diffusion tube
    ​Nitrogen dioxide diffusion tube

The City of London Corporation has been monitoring air quality in the Square Mile since the late 1960s. Monitoring initially focused on sulphur dioxide and black smoke in response to the introduction of the Clean Air Acts.

The City is an Air Quality Management Area for nitrogen dioxide and fine particles (PM10) so monitoring now focuses on these pollutants.

Historic air quality data is summarised in the air quality annual reports.

Continuous analysers

Continuous analysers are used to monitor air quality 24-hrs a day at:

  • Sir John Cass School, an urban background site
  • Beech Street, a roadside site
  • Upper Thames Street, a roadside site
  • Walbrook Wharf, Upper Thames Street, a roadside site
  • Farringdon Street, a roadside site

Data from the City's sites forms part of, and can be downloaded from, the London Air Quality Network (LAQN). The LAQN formed in 1993 to co-ordinate and improve air pollution monitoring in London and is operated and managed by the Environment Research Group at King's College London.

Diffusion tubes

Diffusion tubes are used to monitor nitrogen dioxide at:

  • Speed House, Barbican Centre, urban background site
  • St. Batholomew's Hospital, urban background site
  • St. Dunstan's Church, Fleet Street, roadside site
  • St. Andrew's Church, Queen Victoria Street, roadside site
  • Guinness Trust Estate, Mansell Street, roadside site

Long term data from the diffusion tubes is included in the annual reports.

The City's Air Quality Champions are also monitoring air quality in the City.


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