Environmental exposure to nitrogen dioxide (NO2) during pregnancy and to a lesser extent after birth, is associated with impairment of attentional function in boys and girls evaluated at 4 or 5 years of age. This was the conclusion of a new study by ISGlobal, an organisation supported by the ”la Caixa” Foundation. These findings once again highlight the negative impact of air pollution on health, especially in children.
NO2 is one of the pollutants found in the air we breathe in cities, produced mainly by vehicular traffic. A relationship has been found between both prenatal and postnatal exposure to air pollution and slower cognitive development in childhood, but very few studies have assessed the association between air quality and attentional function.
The INMA - Infancia y Medio Ambiente (Environment and Childhood) project studied almost 1,300 boys and girls from birth cohorts in Valencia, Sabadell, Asturias and Guipúzcoa (Spain) from the prenatal period up to 4 or 5 years of age, between 2003 and 2008. Prenatal and postnatal NO2 levels were measured in the participant’s homes, and attention function was measured at age 4 or 5 using the Conners Kiddie Continuous Performance Test (K-CPT).
The study, which has been published in the journal Environment International, found that higher exposure to the pollutant NO2, mainly during pregnancy and to a lesser extent during the postnatal period, was associated with a delay of almost 2 months in the development of attentional function in the children studied. No marked variations between regions were found, and the association was observed mainly in girls.
These findings are consistent with those of a recent study in the BREATHE project, coordinated by ISGlobal, which reported an impairment in children’s attention function on the days when they were exposed to higher ambient levels of NO2 and elemental carbon (or black carbon), two traffic-related pollutants. In that study, the children were older (between 6 and 12 years of age), there was no prenatal data, and the air pollution levels were recorded in schools rather than in homes.
Alexis Sentís, first author of the study and ISGlobal researcher, explains that “the study shows that exposure to air pollution may even have negative effects on the child before birth and the impact of prenatal exposure may be greater than that of exposure after birth”.
Mònica Guxens, the ISGlobal researcher who coordinated the study, points out that “the clinical impact of this attentional deficit is still unknown, but it may have implications for the entire population because exposure is so generalised”. She goes on to say, “This study provide new evidence demonstrating the need for urgent action to reduce pollution; otherwise the learning capacity of our children could be impaired”.
Prenatal and postnatal exposure to NO2 and child attentional function at 4-5years of age. Sentís A, Sunyer J, Dalmau-Bueno A, Andiarena A, Ballester F, Cirach M, Estarlich M, Fernández-Somoano A, Ibarluzea J, Íñiguez C, Lertxundi A, Tardón A, Nieuwenhuijsen M, Vrijheid M, Guxens M; INMA Project. Environ Int. 2017 Jul 6; 106:170-177.