Toxic particles from diesel vehicles can work their way through the lungs and into the bloodstream, raising the risk of heart attacks and strokes, researchers have proved for the first time.
The nanoparticles, which cannot be traced by Government measuring equipment, stay in the body for months and tend to build up in areas that are most prone to disease.
Scientists have long known that air pollution is bad for the lungs, but until now they did not know whether exhaust particles were able to penetrate further into the body.
Even this small number of particles might have serious consequencesDr Mark Miller, Edinburgh University
A team at Edinburgh University used harmless gold nanoparticles, at an equivalent size to diesel, in a human experiment that simulated cycling through a city.
By looking at surgically removed body samples they found that the gold had accumulated in the fatty areas inside blood vessels that are responsible for heart attack and strokes.
This tallies with previous research showing that cardiovascular disease, of which stroke is a form, accounts for 80 per cent of the roughly 50,000 premature deaths from air pollution each year in the UK.
The scientists say the findings are particularly worrying as officials only have the capacity to measure the overall volume of pollution particles in the air, rather than their number.
While the overall volume of pollution has been falling, they say the number of the most toxic tiny particles able to get deep inside the body is on the rise.
Dr Nicholas Mills, Professor of Cardiology at Edinburgh and one of the study’s co-authors, said: “We have always suspected that nanoparticles in the air that we breath could escape from the lung and enter the body, but until now there was no proof.
“These findings are of wide importance for human health, and we must now focus our attention on reducing emissions and exposure to airborne nanoparticles.”
While petrol particles are also able to penetrate the lungs, a petrol engine will throw out roughly 50 times fewer particles than a diesel engine of equivalent size, the researchers said.
The particles are also capable of penetrating the masks worn by some cyclists to avoid pollution.
Dr Mark Miller, who led the Edinburgh study, said: “It is striking that particles in the air we breathe can get into our blood where they can be carried to different organs of the body.
“Only a very small proportion of inhaled particles will do this, however, if reactive particles like those in air pollution then reach susceptible areas of the body then even this small number of particles might have serious consequences.”
It is possible to fit filters onto diesel vehicles to reduce the number of particles they emit, however these can make cars and lorries inefficient, burning more fuel overall, as well as more expensive.
The research team said a mandatory imposition of filters on all vehicles was premature.