NO2 exposure in young children linked to poor attention capacity

Poor attention capacity in children aged between 4 and 8 years old has been associated with exposure to air pollution in the first two years of life.

It is recognised that experiencing poor air quality during pregnancy and childhood, can negatively impact brain development, and a study led by the Barcelona Institute for Global Health has built on our understanding of this.

Specifically, the researchers found that exposure to nitrogen dioxide – a pollutant mostly created by road traffic – during the first two years of life is associated with poorer attention capacity in children, especially boys. 

The researchers used data from The INMA Project, which was set up specifically to study the effects of prenatal and early life exposures to pollutants on children’s development.

An earlier INMA study had found a link between exposure to NO2 during pregnancy and childhood to impaired attentional function in children at 4-5 years of age.

The new study dug deeper into this, finding that higher exposure to NO2 between 1.3 and 1.6 years of age was associated with higher hit reaction time (an indicator of inattentiveness) in the attentional function test at 4–6 years of age.

Higher exposure to NO2 between 1.5 and 2.2 years of age was associated with more omission errors.

Above the age of 6, higher exposure to NO2 between 0.3 and 2.2 years was only associated with higher hit reaction time in boys.

Anne-Claire Binter, last author of the study said: ‘These findings underline the potential impact of increased traffic-related air pollution on delayed development of attentional capacity and highlight the importance of further research into the long-term effects of air pollution in older age groups.

‘The prefrontal cortex, a part of the brain responsible for executive functions, develops slowly and it is still maturing during pregnancy and childhood. This makes it vulnerable to exposure to air pollution, which has been linked in animal studies to inflammation, oxidative stress, and impaired energy metabolism in the brain.

‘In boys, the association between exposure to NO2 and attentional function may last longer because their brains mature more slowly, which could make them more vulnerable.

‘This study suggests that early childhood, up to the age of 2, seems to be a relevant period for implementing preventive measures. Even a small effect at the individual level from relatively low levels of exposure, as in this study, can have large consequences at the population level. Exposure to traffic-related air pollution is therefore a determinant of the health of future generations.’

The full research paper can be read here.