Greenpeace demonstrators have scaled statues around London, including the 52-meter (169-foot) Nelson's Column in Trafalgar Square, fitting them with gas masks as part of a campaign to highlight air pollution.

Police say they have arrested eight people. The incident will prove embarrassing to authorities. Demonstrators were arrested on the grounds outside the Houses of Parliament after fitting Oliver Cromwell's statue with a mask, despite security measures.

Greenpeace says a total of 17 statues were being targeted across the capital. Campaigner Areeba Hamid says that if the statutes were real people, many of them would often be breathing dangerous air.

The protest is meant to pressure London mayoral candidates to draw attention to air pollution during London's mayoral election.