Infant mortality rate higher in babies exposed to pollutants such as sulphur dioxide
Babies living in areas with high levels of air pollution have a greater risk of death than those surrounded by cleaner air, a study has found.
It is not the first study to investigate the link between air pollution and infant mortality , but thestudy drew particular focus on different pollutants and its analysis at different points in babies’ lives.
Dr Sarah Kotecha , a researcher at Cardiff University, said the results were difficult for pregnant women and their families to do much about.
“You live where you live and you can’t avoid pollution day in day out,” she said, adding that it was down to policymakers to reduce pollution levels and for researchers to unpick how pollutants affect health. “If you can find out some of the mechanisms you can look at potential interventions,” she added.
A growing body of research has revealed links between different components of air pollution and health issues, including lung problems, heart disease, mental health problems, dementia and low birthweight.
The latest study, yet to be peer-reviewed or published, will be presented at the European Respiratory Society international congress in Madrid.
Kotecha said the research was based on data for almost 8 million live births in England and Wales between 2001 and 2012.
The team divided England and Wales into 35,000 areas, each containing approximately 1,500 residents, and looked at the annual death rates for babies up to one-year-old, together with the average annual levels for three pollutants. These were particulate matter known as PM10, which comes from sources including vehicles and waste incineration, nitrogen dioxide (NO2), and sulphur dioxide (SO2), which is released through burning of fossil fuels in power stations and refineries as well as metal extraction.
For each pollutant the team compared the death rate for babies in the worst fifth of polluted areas with those in the best fifth.
Once factors such as maternal age, deprivation level for the area and birthweight were taken into account, the team said that babies aged up to one year had a greater chance of dying living in areas with the worst air pollution compared with areas with the cleanest air.
The results held across all three pollutants, with the odds of death 7% worse for NO2, 4% worse for PM10 and 19% worse for SO2. Further analysis suggested that of the three pollutants, only SO2 was associated with deaths within a baby’s first 28 days.
The study was unable to prove whether high levels of air pollution were to blame for the increased risk of death in those areas. It also did not take into account levels of indoor air pollution.
Prof Mireille Toledano, an expert in population child health at Imperial College London, said the study confirmed that air pollution is a major public health hazard, adding that current standards are failing to protect people.
She said the latest study had a number of limitations. It looked at average pollution levels over relatively large areas while in reality levels can vary greatly over a small distance – meaning the babies’ true exposure was not captured.
The study also did not take into account fluctuations in air pollution with the weather or over seasons, and did not take into account where the mother spent her pregnancy or factors such as maternal smoking. Toledano said it was also unclear how factors like birthweight were accounted for.
“It is showing there is some kind of additional risk from air pollution for infant death but the way that it has been set up is quite a crude analysis,” said Toledano.
Dr Penny Woods, the chief executive of the British Lung Foundation, said action must be taken to tackle the public health crisis of air pollution – including introducing clean air zones in the most polluted cities.
“The evidence linking infant mortality and air pollution is still emerging but Dr Kotecha’s study, which suggests babies born in the UK’s most polluted areas see a significantly increased risk of death, should be a wake-up call to government,” she said.
A second study found that exposure to PM10 from traffic during pregnancy and children’s early life was linked to a slightly lower lung function of the children at eight years old – although the effect was no longer seen by the time the children were 15.
Wood said the study mirrored previous findings, adding that children cannot protect their own lungs.
“Both these studies concentrate on the damage done by air pollution to some of the most vulnerable members of our society – the very young,” she said.
Air pollution on busy roads has been linked to baldness in men as particles in exhaust fumes destroy a hair growth protein, scientists have found.
