Monitors on the traffic-choked Marylebone Road were showing readings breaching European Union limits on ozone and pollutant particles linked to respiratory and other health problems.
Professor Warren Lenney, of the British Lung Foundation, said air pollution posed a big risk to young children because it can damage their lungs, restricting their airways and making them more prone to asthma. The professor said: ‘We should be breathing normal healthy air with no soot, ozone or toxic nitrogen dioxide because all those things come into your airways and they produce inflammation.
'This then scars the lung tissue which results in smaller airways and can cause asthma, chronic obstructive pulmonary disease and lung cancer.
‘The smog that we are seeing this weekend is as bad as in Dickens’s time in Victorian England.
‘Then, it would have been really bad in November due to all the industrial smoke, but today it is somewhat worse due to the car exhaust fumes.
Pollution in towns and cities including London, Oxford, Sheffield, Liverpool and Leeds was as much as double safe levels, according to official data.
The pollution poses a particular risk to asthmatics, the elderly and heart patients, who are being advised to be vigilant to any change in their conditions and to seek medical help if they experience difficulties.
Research has found that particulate matter causes between 12,000 and 24,000 premature deaths a year in Britain. In 2007 scientists at the University of Southern California found that children who lived within 500 yards of a main road had stunted lung development.
Yesterday 39 sites in the UK exceeded the limit for PM10s. The pollution has been exacerbated by the number of people driving. An estimated 18 million vehicles will travel over this weekend and next.
Simon Birkett, of the Campaign for Clean Air in London, said: “It is a scandal the so-called 'greenest government’ is still virtually silent on the long-term impacts of air pollution on health.”
Time to remember once again the naïve enthusiasm with which the last CEO of the London Cycling Campaign welcomed the prospect of a cycling prime minister and a cycling mayor.
And don’t forget the car dependency and the obesity.