The black cab is one of London’s most famous icons. Along with Piccadilly Circus, Trafalgar Square and the Routemaster bus, it regularly features in stock footage for films set in the capital and retains a nostalgic appeal for many people, particularly visitors to London.

However, figures from Transport for London show a different side to the story. They reveal that, in 2007-8, the 21,000 black cabs in London produced almost the same amount of carbon dioxide (the main greenhouse gas) as the capital’s 46,000 private hire vehicles (PHVs) and even more of the emissions (PM10 and NOx) that are responsible for air pollution. So it is quite clear that black cabs have an adverse environmental impact, both on climate change and air quality, out of proportion to their numbers.

When Ken Livingstone was Mayor of London the annual licensing inspection for cabs was tightened up and in October 2007 an additional mid-year test was introduced. Nearly 40 per cent of cabs failed the test, with excess emissions a major factor. Despite this, Ken’s successor, Boris Johnson, has scrapped the mid-year inspection for black cabs – while retaining them for the less-polluting PHVs.

When I raised the issue of the pollution caused by black cabs at Mayor’s Question Time this month, Boris admitted that emissions of small particulates (PM10) were especially problematic for Londoners suffering from respiratory illnesses and said this issue needed to be “addressed”. But he refused to consider reinstating the twice-yearly checks.

The reason is not hard to find. Some of Boris’ most effective allies during his mayoral campaign were black cab drivers. According to his campaign office, they distributed over seven million receipts with the slogan “Back Boris” to their passengers – a figure equivalent to the entire population of London. In exchange, Boris made a number of promises to the cabbies, including the abolition of the six-monthly test.

It was not as though Ken had treated black cab drivers badly. He gave them exemption from the congestion charge, the right to use central London bus lanes and an increased night-rate tariff. But, unlike Livingstone, Johnson appears happy to sacrifice Londoners’ health and the struggle against climate change for short-term political gain.

Black cabs are a permanent and necessary part of London’s transport network and no one  is proposing to replace them with PHVs. However, as things stand, for the eco-conscious Londoner who needs to use a taxi service, a licensed private hire minicab is the greener option. Black cabs need to clean up their act. The Mayor should take a lead on this crucial issue and do everything he can to reduce emissions – rather than pander to drivers’ convenience in pursuit of electoral advantage.

Published in Tribune, 31 July 2009