Air pollution ‘leaves children prone to high blood pressure’

Air pollution could raise children’s risk of developing high blood pressure in later life, especially if they are overweight.

Children should be encouraged to walk home from school along quieter roads, while schools should shield playgrounds with trees to absorb pollution, experts warn.

Researchers led by King’s College London analysed eight studies involving around 15,000 children aged 10 to 19.

They were interested in children’s exposure to pollution such as microscopic PM2.5 particles, found in car exhaust fumes, and PM10 particles, whose main sources include car tyre fragments thrown up from roads and wood-burning stoves.

At age 12, children exposed to a higher long-term level of PM2.5 and PM10, which can be inhaled straight into the lungs, had significantly higher blood pressure.

Children should be encouraged to walk home from school along quieter roads, while schools should shield playgrounds with trees to absorb pollution, experts warn

This could lead to high blood pressure in adulthood, and an increased risk of heart attacks and strokes.

Children who were overweight and obese had almost double the rise in blood pressure compared to normal-weight children when exposed to higher levels of ozone pollution, which also comes from car fumes, and sulphur dioxide, which is mainly produced by coal-burning.

Professor Seeromanie Harding, who led the scientific review, from King’s College London, said: ‘Children are more exposed to pollution, as they spend more time outside doing things like playing football or other sports, or spending time outside shopping centres with their friends.

‘Worryingly, they are also more vulnerable to pollution and to changes in blood pressure, as they are still growing and developing.

‘These concerning results mean that children in polluted areas are likely to develop high blood pressure in later life, raising their risk of heart problems and strokes.

‘Parents may want to encourage their children to choose to walk along roads with less traffic and lower pollution, while schools may need to consider speed limits and tree-planting to keep playgrounds protected from pollution.’

Air pollution particles, which are inhaled deep into the body, can get into the bloodstream, causing damage to the lining of blood vessels.

This can make blood vessels harder and less elastic, so the heart needs to pump faster to force blood through them – raising blood pressure.

The evidence so far on how this affects children has been mixed and mainly relies on studies in China, which is very polluted.

The new scientific review, however, includes five studies in Germany, the Netherlands and Denmark, which have similar levels of pollution to the UK.

The review found children exposed to higher levels of PM10 and nitrogen dioxide typically had higher blood pressure, but this was not statistically significant, potentially because a relatively low number of children were analysed.

However the strongest result, for around 3,700 children who were aged 12, showed those exposed to a higher level of PM2.5 and PM10 – for a year or longer – did have significantly higher diastolic blood pressure.

This is the lower number of a blood pressure reading, which measures the ‘resting’ pressure between heartbeats.

For 12-year-olds, higher PM10 exposure over a year or longer was also significantly linked to higher systolic blood pressure – the higher number in a blood pressure reading, which shows the blood pressure in arteries when the heart beats.

There was no link found between blood pressure and short-term exposure to pollution across the studies, which overall provided low-quality evidence.

However researchers point out that the data may have been flawed because the studies typically relied on air quality measurements around children’s homes, when in fact children spend most of their time at school.

Professor Harding said: ‘Previous evidence shows children’s diastolic blood pressure goes up by about seven points between the age of 10 and 19.

‘These new results show a rise of around five points due to pollution, which is a large percentage.

‘It is vital we have more research on this, and take action to protect children.’

WHAT HAVE RECENT STUDIES SHOWN POLLUTION CAN DO TO OUR HEALTH AND BODIES?

CAUSE CHILDREN TO HAVE A LOW IQ: Researchers at the University of California, San Francisco, found in May 2019 that children born to mothers who live in polluted areas have an IQ that is up to seven points lower than those living in places with cleaner air.

CAUSE CHILDREN TO HAVE POORER MEMORY: Researchers at the Barcelona Institute for Global Health found boys exposed to greater levels of PM2.5 in the womb performed worse on memory tests by the time they are 10.

DELAY THE DEVELOPMENT OF CHILDREN: Youngsters who live less than one-third of a mile away from busy roads are twice as likely to score lower on tests of communication skills in infancy, found researchers at Eunice Kennedy Shriver National Institute of Child Health in April. They were also more likely to have poorer hand-eye coordination.

MAKE CHILDREN MORE ANXIOUS: University of Cincinnati scientists claimed pollution may alter the structure of children’s brains to make them more anxious. Their study of 14 youngsters found rates of anxiety was higher among those exposed to greater levels of pollution.

CUT YOUR CHILD’S LIFE SHORT: Children born today will lose nearly two years of their lives because of air pollution, according to a report by the US-based Health Effects Institute and the University of British Columbia in April 2019. UNICEF called for action on the back of the study.

RAISE A CHILD’S RISK OF AUTISM: Researchers at Monash University in Australia discovered youngsters living in highly polluted parts of Shanghai have a 86 per cent greater chance of developing ASD. Lead author Dr Yuming Guo said: ‘The developing brains of young children are more vulnerable to toxic exposures in the environment.’

CAUSE ASTHMA IN CHILDREN: Four million children around the world develop asthma each year because of road traffic pollution, a major study by academics at George Washington University estimated. Experts are divided as to what causes asthma – but exposure to pollution in childhood increases the risk by damaging the lungs.

MAKE CHILDREN FAT: University of Southern California experts found last November that 10 year olds who lived in polluted areas when they were babies are, on average, 2.2lbs (1kg), heavier than those who grew up around cleaner air. Nitrogen dioxide pollution could disrupt how well children burn fat, the scientists said.

LEAVE WOMEN INFERTILE EARLIER: Scientists at the University of Modena, Italy, claimed in May 2019 that they believe pollution speeds up ageing in women, just like smoking, meaning they run out of eggs faster. This was based on them finding almost two-thirds of women who have a low ‘reserve’ of eggs regularly inhaled toxic air.

RAISE THE RISK OF A MISCARRIAGE: University of Utah scientists found in January that pregnant women are 16 per cent more likely to suffer the heartbreak of a miscarriage if they live in areas of high pollution.

RAISE THE RISK OF BREAST CANCER: Scientists at the University of Stirling found six women working at the same bridge next to a busy road in the US got breast cancer within three years of each other. There was a one in 10,000 chance the cases were a coincidence, the study said. It suggested chemicals in the traffic fumes caused the cancer by shutting down the BRCA genes, which try to stop tumours growing.

DAMAGE A MAN’S SPERM: Brazilian scientists at the University of Sao Paulo found in March that mice exposed to toxic air had lower counts and worse quality sperm compared to those who had inhaled clean air since birth.

MAKE MEN LESS LIKELY TO GET SEXUALLY AROUSED: Scientists at Guangzhou Medical University in China found rats exposed to air pollution struggled to get sexually aroused. Scientists believe it may also affect men, as inhaling poisonous particles may trigger inflammation in blood vessels and starve the genitals of oxygen – affecting men’s ability to become sexually aroused.

MAKE MEN MORE LIKELY TO HAVE ERECTILE DYSFUNCTION: Men who live on main roads are more likely to have difficulty getting an erection due to exposure to pollution, a Guangzhou University in China study suggested in February. Toxic fumes reduced blood flow to the genitals, tests on rats showed, putting them at risk of developing erectile dysfunction.

RAISE THE RISK OF PSYCHOSIS: In March, King’s College London scientists linked toxic air to intense paranoia and hearing voices in young people for the first time. They said uncovering exactly how pollution may lead to psychosis should be an ‘urgent health priority’.

MAKE YOU DEPRESSED: Massachusetts Institute of Technology researchers found in January that that the more polluted the air, the sadder we are. Their study was based on analysing social media users in China alongside the average daily PM2.5 concentration and weather data where they lived.

CAUSE DEMENTIA: Air pollution could be responsible for 60,000 cases of dementia in the UK, researchers from King’s College London and St George’s, University of London, calculated last September. Tiny pollutants breathed deep into the lungs and enter the blood stream, where they may travel into the brain and cause inflammation – a problem which may trigger dementia.

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