Europeans no longer see the kind of pollution that within living memory killed thousands of Londoners in the Great Smog of 1952, but the air they breathe still bears invisible threats scarcely less deadly, and little more controlled.

Poorer air quality is shortening lives

While attention is given to curbing the carbon dioxide (CO2) emissions blamed for global warming, substances more directly harmful to human health, notably nitrogen oxides, are pumped out of diesel engines and from European power stations burning coal that is getting cheaper as Americans exploit new gas reserves.

The result, say those campaigning for change, is ever poorer air quality shortening lives. Yet a move by the European Commission to tighten vehicle emissions rules is being challenged by some car makers.

And, with businesses and governments in Europe desperately short of cash for new regulation or technologies, broader new air quality legislation can also expect opposition when the EU executive proposes it to member states, probably this year.

The Commission has deployed its own data, showing huge costs from pollution and substantial and growing public support for a clean-up that could benefit firms offering cleaner technologies.

But health campaigners trying to push up the public agenda an issue that they compare in gravity to smoking face a problem:

“One of the big difficulties in communicating this issue is it is not visible in the way London smogs in the 1950s were,” said Simon Moore at the Policy Exchange think-tank in London.

Over a weekend in December 1952, cold air, fog on the Thames and coal smoke belching from a million homes and factories made the Great Smog. In places, people walking lost sight of their feet, cattle were reported asphyxiated at a market and 4,000 or more people died as a result.

That and numerous less dramatic events across Europe spawned clean air laws from the 1950s that got rid of visible smoke. But for all the catalytic conversion and other means to cut down CO2 emissions, unseen pollution, notably from traffic, has worsened. In all, nearly half a million of the half-billion citizens of the EU die a premature death each year because of the air they breathe, according to the European Environment Agency (EEA), an official EU organisation.

Countering fears of the cost of regulation, it puts the EU bill for healthcare, sick days and the wider impact on the environment at roughly €1 trillion.

London, the continent’s biggest city, has one of the biggest problems with air. It has the highest levels of nitrogen dioxide (NO2) of any European capital; the colourless, odourless gas is produced by burning fuel and can damage people’s breathing. Through complex chemical reactions, nitrogen oxides generate ground-level ozone; this has supplanted the old London ‘pea soup’ smoky fogs as the modern definition of smog.

Air in the British capital again made headlines when ground-level ozone was 80 per cent over World Health Organisation (WHO) guidelines on the eve of the 2012 Olympics, raising worries for the athletes.

Critics complain that successive governments have done too little to combat toxic air, which they say is Britain’s biggest killer after smoking. It causes 29,000 early deaths a year in a country of 63 million.