Exposure to polluted air in the womb and during the first eight and a half years of a child’s life can alter the brain, according to a new study.
The research, published in the Environmental Pollution journal, has established an association between air pollution and white matter microstructure.
Traces of cerebral white matter ensure connectivity between different areas of the brain. This connectivity can be measured by observing the microstructure of this white matter as a marker of typical brain development.
Experts at the Barcelona Institute for Global Health who led the study say the findings are significant because abnormal white matter structure has been linked to mental health illnesses such as depression and anxiety.
The study found that the greater a child’s exposure to pollution before the age of five, the more the brain structure was altered.
Researchers found that exposure to particulate matter in the first two years of life – particles of dust, dirt, soot, smoke or polluting liquids – the greater the volume of the putamen.
This is a brain structure involved in motor function and learning processes, but with less specialised functions than the cortical structures.
“A larger putamen has been associated with certain psychiatric disorders (schizophrenia, autism spectrum disorders, and obsessive-compulsive spectrum disorders),” ISGlobal researcher Anne-Claire Binter, who co-authored the study, said.
“One of the important conclusions of this study is that the infant’s brain is particularly susceptible to the effects of air pollution not only during pregnancy, as has been shown in earlier studies, but also during childhood.”
The study analysed the effects of air pollution on 3,515 children every month until they turned eight years and six months.
To determine the level of exposure, experts estimated the daily levels of nitrogen dioxide and particulate matter in the children’s homes during the mother’s pregnancy and in their early lives.
Following their ninth birthday, the children underwent imaging to examine the structural connectivity in their brains and volumes of various brain structure.
According to Public Health England (PHE), air pollution is the biggest environmental threat to health in the UK. PHE estimates that between 28,000 and 36,000 deaths can be attributed to long-term exposure to polluted air each year.