What those diesel fumes are REALLY doing to your health
Heart attacks. Stroke. Dementia. Even wrecking your sleep . . .
TAKING a breath of ‘fresh air’ may not be quite as healthy as you thought. Air pollution has become a major health problem with World Health Organization (WHO) estimates indicating that more than 400,000 premature deaths can be attributed to poor air quality in Europe annually.
In Ireland alone, the number of deaths attributable to air pollution is estimated at 1,200 people every year mainly due to cardiovascular disease, while in Britain, at least 40,000 deaths a year are thought to be caused by air pollution. It is well known that pollution can aggravate and possibly trigger health conditions such as asthma. ‘Over short periods, high pollution levels can cause damage to the lining of our lungs,’ explains Stephen Spiro, a professor of respiratory medicine. ‘This can lead to coughing, wheeziness and breathlessness, particularly among people with a pre-existing lung condition.’
But other conditions, from stroke to cancer, are increasingly being linked to air pollution. One of the major culprits is traffic fumes — about a third of our air pollution is from transport, explains Alastair Lewis, a leading professor of atmospheric chemistry.
This pollution consists largely of nitrogen dioxide — most of which comes from diesel engines — and fine particles known as particulates, released from exhausts and by the wearing down of brakes and tyres. ‘Almost every combustion process — such as functioning power stations — produces particulates,’ adds Professor Lewis.
‘The difference with cars is that unlike power stations, they are everywhere and close to where many people live. So the pollution they cause is disproportionately more important for public health.’
POLLUTING particles of soot, carbon and from aerosols are categorised by size and typically divided into two groups: coarse particles less than ten micrometres wide, known as PM10, and fine particles less than 2.5 micrometres wide (PM2.5).
Last week, diesel vehicles were described as one of the ‘worst offenders’ for PM2.5 by researchers who found that even PM2.5 levels well within the EU maximum can cause inflammation in the body and raise blood pressure.
In a study funded by the British Heart Foundation (BHF) and the Wellcome Trust, the researchers found that the greater the exposure to this size of particulate, ‘the larger the heart becomes and the worse it performs’, raising the risk of death from heart disease. ‘This adds to the growing evidence that air pollution, particularly from small particles in diesel fumes, is dangerous for your heart and health,’ said Professor Jeremy Pearson, the BHF’s associate medical director.
And the smaller the particulate, the more harmful, it seems. ‘Ultra-fine particles even smaller than PM2.5 can penetrate the skin and enter the lungs much more easily,’ says Prashant Kumar, a leading professor in air quality and health.
This month researchers at Imperial College London revealed that tiny diesel particles just 0.1 micrometres in diameter can directly affect the lungs and cause tighter airways and coughing.
Meanwhile last year, the WHO, found that Longford town was one of 11 areas across Ireland and Britain that breached the safe limit set for PM10. Towns including Armagh, Bray, Belfast, Derry, Galway and Dublin were also found to have breached the safe levels for PM2.5.
As air quality declines, the risk of stroke, heart disease, lung cancer, and chronic and acute respiratory diseases, including asthma, increases. Ireland has one of the highest levels of COPD in Europe and so this is a real concern. This ambient air pollution, made of these high concentrations of small and fine particulate matter, is the greatest environmental risk to health — and the cause of more than 3 million premature deaths across the world every year.
Here, with the help of leading experts, we reveal the latest evidence on what traffic pollution could be doing to your health . . .
HOW THEY CAN HURT YOUR HEART
ALMOST one stroke in three is triggered by air pollution, according to a worldwide study by Auckland University of Technology, in New Zealand.
The research, published last year, found air pollution was among the top ten causes of stroke, along with betterknown risks such as smoking.
One theory is that over the long term, air pollution makes blood thicker and this in turn raises blood pressure, so boosting the risk of clots in the brain.
But even short-term exposure to air pollutants such as nitrogen dioxide and particulates increased the risk of hospital admission or death from stroke in the following seven days, according to a review of studies involving six million people published in 2015 by Edinburgh University.
‘The evidence suggesting air pollution as a risk factor for stroke is very strong,’ says Pippa Tyrrell, a professor of stroke medicine. ‘It’s vital this issue is addressed by the Government. But in the meantime it is even more important to avoid other stroke risk factors and take more exercise.’ There is also a strong link between pollution and heart problems, says Professor David Newby, BHF John Wheatley Chair of Cardiology at Edinburgh University — as an acute trigger causing a heart attack, for example, or associated with long-term heart disease.
‘The mechanism isn’t exactly clear but these tiny particles may get deep into the lungs, then into the bloodstream,’ says Professor Newby. ‘This affects the blood cells, causing blood to become stickier and more likely to clot.’
He adds that compounds on the surface of particles of pollution are associated with processes that could lead to the build-up of fatty material inside the arteries.
BAD NEWS FOR YOUR SLEEP
AIR pollution could be to blame for bad sleep, too. A study presented to the American Thoracic Society conference this month measured how long participants spent asleep and found their quality of sleep was affected by air pollution: the more exposure someone had to nitrogen dioxide and PM2.5, the worse their chances of a good night’s sleep. ‘Your nose, sinuses and the back of your throat can all be irritated by those pollutants, so that can cause some sleep disruption,’ says Martha Billings, a professor at the University of Washington, who led the research.
Study volunteers with raised nitrogen dioxide in their bodies were up to 60per cent more likely to suffer from sleep deprivation than those living in areas with lower pollution levels.
THEY CAN MAKE YOUR EYES ACIDIC
HIGH levels of air pollution can raise the risk of dry eye syndrome as well as allergic conjunctivitis — inflammation of the eye.
‘Particulates from diesel emissions can act as an irritant to the surface of the eye, causing dryness and irritation,’ says Marsel Bregu, a consultant ophthalmologist.
Contact lenses may make matters worse, as particulates can lodge between the contact lens and the surface of the eye. ‘We have been seeing more cases of dry eyes in the past few years, as well as the inflammatory condition red eye. There must be a correlation between this and air pollution,’ says Mr Bregu.
There is a direct correlation between pollution levels and various eye infections, according to a study by the All India Institute of Medical Sciences in 2002. The researchers also suggested that high levels of air pollutants such as nitrogen dioxide make the tear film of the eyes more acidic.
‘This could cause a burning, stinging discomfort to the
eyes,’ says consultant ophthalmologist Dr Jeff Kwartz.
A WORRYING LINK TO CANCER
POLLUTION has contributed to a 10 per cent rise in cancer diagnoses, according to a study by the University of Illinois, published this month.
While someone’s chance of developing the disease may be partly down to genetics, the report’s authors say it could also be that pollution damages DNA and the way hormones function, leading to cancer.
Air pollution caused by traffic and industry may increase the risk of lung cancer independently of factors such as smoking and age, according to research by the Norwegian Institute of Public Health. Analysing data from more than 16,000 men between 1971 and 1998, the researchers estimated that the risk of developing lung cancer was 8 per cent higher for men living where levels of nitrogen dioxide, mainly produced by traffic, were higher.
It could be that inhaled pollutants damage DNA in the lung cells. Or soot particles may get lodged deep in the lungs, causing long-term inflammation. This could increase the rate at which cells divide and the chance of random mutations growing and spreading.
WHY THEY CAN TRIGGER ECZEMA AND AGE SPOTS
AIR pollution is a particular issue for those with eczema. This condition occurs when the skin barrier — the outermost protective layer of skin — does not work, explains Daniel Glass, a respected consultant dermatologist. ‘So those who are genetically predisposed to eczema may find it is triggered by air pollution.’
He adds that as eczema is associated with the subsequent development of asthma, pollution increases the likelihood of both.
Pollution also damages skin cells, speeding up breakdown of the collagen that keeps our skin supple and eventually leading to problems with pigmentation and wrinkles. Particulates have been linked to signs of ageing in the skin, especially pigment spots and more pronounced nasolabial folds, according to a 2010 study published in the Journal of Investigative Dermatology. The researchers looked at the skin of 400 women living either in rural areas or near busy roads in Germany and marked out signs of ageing such as pigmentation and wrinkles. Almost all had remained at the same address for the previous 30 years. The study concluded that pollution may have caused skin ageing by triggering oxidative stress. ‘The study suggests that because of exposure to pollution, the skin is hindered from repairing itself, leading to signs of ageing,’ says Andrew Wright, a professor of dermatology.
RISK OF PROBLEMS IN PREGNANCY
EXPECTANT mothers living close to busy roads are at greater risk of serious complications because of their exposure to air pollution, research suggests.
This year, a study led by the University of Copenhagen of 73,000 women found that preeclampsia — a form of high blood pressure that affects 2 to 3% of pregnant women each year — is made more likely by noise and pollution from roads.
Researchers believe the toxins may raise stress levels and cause inflammation leading to rising blood pressure. In severe cases, pre-eclampsia can lead to stillbirth or be fatal to the mother.
‘There is robust evidence to link low birth weight with exposure to pollution such as diesel,’ says Jonathan Grigg, a professor of paediatric respiratory and environmental medicine.
‘The theory is that the particles of pollution may produce inflammation in the mother’s lungs which then triggers mediators — substances released from cells — that leach into the blood and affect development of the child.’
This year, researchers from the Stockholm Environment Institute also found that particulates under 2.5micrometres could be to blame for millions of premature births globally each year.
COULD THEY CAUSE DIABETES?...
RESEARCHERS in Munich found that children living in polluted areas were more likely to develop insulin resistance — a precursor to type 2 diabetes — by the age of ten. They suggest the link is due to inflammation in the body caused by cells reacting to air pollution particles.
Meanwhile, a 2012 study of 4,000 women living in Los Angeles by Boston University found that those living in polluted areas were more likely to have high blood pressure and type 2 diabetes. Jim Zhang, professor of global and environmental health at Duke University in the U.S, who has researched links between diabetes and pollution, told Good Health: ‘The evidence is mounting to support the link between air pollution and risk factors for diabetes.’
... AND MAKE BONES CRUMBLE FASTER
AIR pollution has been shown to accelerate the development of osteoporosis, according to recent research. Amit Amin, an orthopaedic surgeon says pollution exacerbates other issues.
‘Advanced age, menopause, smoking, excessive alcohol consumption and a sedentary lifestyle are the most common risk factors but pollution is likely to contribute to the breakdown of bone cells, raising the chance of developing osteoporosis,’ he says.