Videos on YouTube show cars driving through the Dartford and Blackwall tunnels and the Limehouse Link.

BBC: East London police to monitor tunnel running events

The fleet of three lorries is patrolling 19 miles (30km) of roads with some of the worst pollution, including Victoria Embankment, Earl's Court Road, roads leading to the Blackwall Tunnel and in the Euston area.

BBC: Boris Johnson sticks by gluing pollution to roads