Inhaled nanoparticles – like those released from vehicle exhausts – can work their way through the lungs and into the bloodstream, potentially raising the risk of heart attack and stroke, according to new research part-funded by the British Heart Foundation.
The findings, published in the journal, ACS Nano, build on previous studies that have found tiny particles in air pollution are associated with an increased risk of cardiovascular disease, although the cause remains unproven.
However, this research shows for the first time that inhaled nanoparticles can gain access to the blood in healthy individuals and people at risk of stroke. Most worryingly, these nanoparticles tend to build-up in diseased blood vessels where they could worsen coronary heart disease – the cause of a heart attack.
It is not currently possible to measure environmental nanoparticles in the blood. So, researchers from the University of Edinburgh, and the National Institute for Public Health and the Environment in the Netherlands, used a variety of specialist techniques to track the fate of harmless gold nanoparticles breathed in by volunteers.
They were able to show that these nanoparticles can migrate from the lungs and into the bloodstream within 24 hours after exposure and were still detectable in the blood three months later. By looking at surgically removed plaques from people at high risk of stroke they were also able to find that the nanoparticles accumulated in the fatty plaques that grow inside blood vessels and cause heart attacks and strokes.
Cardiovascular disease (CVD) – the main forms of which are coronary heart disease and stroke – accounts for 80 per cent of all premature deaths from air pollution.
Dr Mark Miller, Senior Research Scientist at the University of Edinburgh, who led the 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.’
Around the world, air pollution is responsible for millions of deaths from heart attack and stroke each year. But how particles inhaled into the lungs can affect blood vessels and the heart has remained a mystery. The current findings add to a large body of evidence that inhaled particles can damage our heart and blood vessels in many different ways.
Dr Nicholas Mills, Professor of Cardiology, and a co-author of the work, said, ‘We have always suspected that nanoparticles in the air that we breathe could escape from the lungs 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.’