Babies exposed to air pollution when they’re still in the womb may end up with higher blood pressure as a child, a new study suggests.
Researchers studied effects of exposure to environmental factors such as pollution, noise and a densely-built environment on babies both before and after birth.
The experts, from the Barcelona Institute for Global Health, looked at mothers and babies based in six European cities, including Bradford in the UK.
They found a link between high blood pressure as a child and exposure to high levels of air pollution, as well as building density, noise, low proximity to green spaces and low socio-economic status.
Hypertension – high blood pressure – is one of the main risk factors of cardiovascular diseases, such as coronary artery disease and heart attacks.
The experts say urban planners need to take into account the effects of such factors to save children from cardiovascular diseases by the time they reach adulthood.
Researchers studied blood pressure of babies from six European cities, including Bradford in West Yorkshire (pictured)
‘Our results show that, from conception onwards, the urban environment can affect blood pressure in preschool children,’ said study author Charline Warembourg at Barcelona Institute for Global Health.
‘This means that a commitment to urban design and transport planning designed to reduce damaging environmental exposures has the potential to reduce the risk of cardiovascular disease in adulthood.’
To study the impact of urban exposures on children, the research team analysed data from 4,279 children aged between four to five years old.
The children were living in one of six European cities – Bradford in the UK, Poitiers and Nancy in France, Sabadell and Valencia in Spain and Heraklion in Greece.
The team assessed multiple aspects of the children’s environment – initially, during the prenatal period, the place of residence of the mothers during their pregnancy, and subsequently the homes of the children after birth.
Factors studied included the built environment, natural spaces, traffic, air pollution, noise, climate and level of social and economic hardship.
Hypertension – high blood pressure – is one of the main risk factors of cardiovascular diseases
Assessing the children’s blood pressure when they were between four and five years of age allowed them to study the long-term effect of the exposures analysed.
Analysis of the results showed that exposure to higher levels of air pollution, particularly during the first two terms of pregnancy, was associated with higher blood pressure in childhood.
The team considered levels of nitrogen dioxide (NO2), a pollutant that’s already known to cause health issues like inflaming airways while aggravating existing heart and lung diseases.
A 9.1 microgram per cubic metre (μg/m3) increase in NO2 was associated with a 0.9 millimetre of mercury increase in diastolic blood pressure, the team found.
The limit value established by the World Health Organisation (WHO) to protect the population from the damaging effects of NO2 is 40 μg/m3, a threshold exceeded on a regular basis in cities like Barcelona and Madrid.
Other characteristics of the urban environment during childhood is also important, the team found.
High building density was associated with higher blood pressure, while good urban transport connectivity was found to be linked with lower blood pressure.
‘It is possible that these associations reflect how people move around in the city and may indicate that greater connectivity promotes physical activity in the population,’ said Warembourg.
Exposure to noise also appears to be associated with higher blood pressure in children.
According to the WHO, road traffic noise is considered as a risk factor for hypertension, likely due to the physiological stress response.
Based on their analysis, the authors said one in every five children lives in an urban environment characterised by levels of air pollution, noise and building density associated with blood pressure values higher than those observed in children not exposed to these environmental factors.
Tower blocks in Valencia, Spain. Researchers say designing cities that promote healthy environments is of high importance
High blood pressure is one of the chief risk factors for cardiovascular disease, a condition which is currently the leading cause of death worldwide.
‘Numerous studies have shown that children with higher blood pressure are more likely to develop hypertension later in life,’ says Martine Vrijheid, study leader and director of Barcelona Institute for Global Health’s Childhood and Environment Programme.
‘The results of this study show how important it is to identify environmental exposures that contribute to hypertension in early life, from conception onwards.’
Given the increasing urbanisation of the world’s population, the role that urban design and transport plays in health is ‘a topic of growing concern’, the team warn.
The urban population of the world has grown rapidly since the 1950s by 2050, 68 per cent of the world population projected to live in urban areas, according to the UN.
‘This growth in urbanisation will increase the number of people exposed to adverse urban factors and will impact on health and health services over the long term,’ they say in their paper, published in Environment International.
‘However tackling the root causes to prevent such exposures through urban design to promote physical activity and reduce environmental hazards may be more appropriate.’
Revealed: MailOnline dissects the impact greenhouse gases have on the planet – and what is being done to stop air pollution
Emissions
Carbon dioxide
Carbon dioxide (CO2) is one of the biggest contributors to global warming. After the gas is released into the atmosphere it stays there, making it difficult for heat to escape – and warming up the planet in the process.
It is primarily released from burning fossil fuels such as coal, oil and gas, as well as cement production.
The average monthly concentration of CO2 in the Earth’s atmosphere, as of April 2019, is 413 parts per million (ppm). Before the Industrial Revolution, the concentration was just 280 ppm.
CO2 concentration has fluctuated over the last 800,000 years between 180 to 280ppm, but has been vastly accelerated by pollution caused by humans.
Nitrogen dioxide
The gas nitrogen dioxide (NO2) comes from burning fossil fuels, car exhaust emissions and the use of nitrogen-based fertilisers used in agriculture.
Although there is far less NO2 in the atmosphere than CO2, it is between 200 and 300 times more effective at trapping heat.
Sulfur dioxide
Sulfur dioxide (SO2) also primarily comes from fossil fuel burning, but can also be released from car exhausts.
SO2 can react with water, oxygen and other chemicals in the atmosphere to cause acid rain.
Carbon monoxide
Carbon monoxide (CO) is an indirect greenhouse gas as it reacts with hydroxyl radicals, removing them. Hydroxyl radicals reduce the lifetime of carbon dioxide and other greenhouse gases.
Particulates
What is particulate matter?
Particulate matter refers to tiny parts of solids or liquid materials in the air.
Some are visible, such as dust, whereas others cannot be seen by the naked eye.
Materials such as metals, microplastics, soil and chemicals can be in particulate matter.
Particulate matter (or PM) is described in micrometres. The two main ones mentioned in reports and studies are PM10 (less than 10 micrometres) and PM2.5 (less than 2.5 micrometres).
Air pollution comes from burning fossil fuels, cars, cement making and agriculture
Scientists measure the rate of particulates in the air by cubic metre.
Particulate matter is sent into the air by a number of processes including burning fossil fuels, driving cars and steel making.
Why are particulates dangerous?
Particulates are dangerous because those less than 10 micrometres in diameter can get deep into your lungs, or even pass into your bloodstream. Particulates are found in higher concentrations in urban areas, particularly along main roads.
Health impact
What sort of health problems can pollution cause?
According to the World Health Organization, a third of deaths from stroke, lung cancer and heart disease can be linked to air pollution.
Some of the effects of air pollution on the body are not understood, but pollution may increase inflammation which narrows the arteries leading to heart attacks or strokes.
As well as this, almost one in 10 lung cancer cases in the UK are caused by air pollution.
Particulates find their way into the lungs and get lodged there, causing inflammation and damage. As well as this, some chemicals in particulates that make their way into the body can cause cancer.
Deaths from pollution
Around seven million people die prematurely because of air pollution every year. Pollution can cause a number of issues including asthma attacks, strokes, various cancers and cardiovascular problems.
Asthma triggers
Air pollution can cause problems for asthma sufferers for a number of reasons. Pollutants in traffic fumes can irritate the airways, and particulates can get into your lungs and throat and make these areas inflamed.
Problems in pregnancy
Women exposed to air pollution before getting pregnant are nearly 20 per cent more likely to have babies with birth defects, research suggested in January 2018.
Living within 3.1 miles (5km) of a highly-polluted area one month before conceiving makes women more likely to give birth to babies with defects such as cleft palates or lips, a study by University of Cincinnati found.
For every 0.01mg/m3 increase in fine air particles, birth defects rise by 19 per cent, the research adds.
Previous research suggests this causes birth defects as a result of women suffering inflammation and ‘internal stress’.
What is being done to tackle air pollution?
Paris agreement on climate change
The Paris Agreement, which was first signed in 2015, is an international agreement to control and limit climate change.
It hopes to hold the increase in the global average temperature to below 2°C (3.6ºF) ‘and to pursue efforts to limit the temperature increase to 1.5°C (2.7°F)’.
Carbon neutral by 2050
The UK government has announced plans to make the country carbon neutral by 2050.
They plan to do this by planting more trees and by installing ‘carbon capture’ technology at the source of the pollution.
Some critics are worried that this first option will be used by the government to export its carbon offsetting to other countries.
International carbon credits let nations continue emitting carbon while paying for trees to be planted elsewhere, balancing out their emissions.
No new petrol or diesel vehicles by 2040
In 2017, the UK government announced the sale of new petrol and diesel cars would be banned by 2040.
However, MPs on the climate change committee have urged the government to bring the ban forward to 2030, as by then they will have an equivalent range and price.
The Paris Agreement, which was first signed in 2015, is an international agreement to control and limit climate change. Pictured: air pollution over Paris in 2019.
Norway’s electric car subsidies
The speedy electrification of Norway’s automotive fleet is attributed mainly to generous state subsidies. Electric cars are almost entirely exempt from the heavy taxes imposed on petrol and diesel cars, which makes them competitively priced.
A VW Golf with a standard combustion engine costs nearly 334,000 kroner (34,500 euros, $38,600), while its electric cousin the e-Golf costs 326,000 kroner thanks to a lower tax quotient.
Criticisms of inaction on climate change
The Committee on Climate Change (CCC) has said there is a ‘shocking’ lack of Government preparation for the risks to the country from climate change.
The committee assessed 33 areas where the risks of climate change had to be addressed – from flood resilience of properties to impacts on farmland and supply chains – and found no real progress in any of them.
The UK is not prepared for 2°C of warming, the level at which countries have pledged to curb temperature rises, let alone a 4°C rise, which is possible if greenhouse gases are not cut globally, the committee said.
It added that cities need more green spaces to stop the urban ‘heat island’ effect, and to prevent floods by soaking up heavy rainfall.
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