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An analysis of epidemiological data from the region of Tarragona, Spain, found that higher prenatal exposure to air pollution was associated with higher teacher-reported attention-deficit/hyperactivity disorder symptoms in school-age children. This pollution included various sizes of particulate matter as well as nitrogen gases. The researchers found no association between exposure to air pollution and the likelihood of receiving an official diagnosis for the disorder. The paper was published in Research on Child and Adolescent Psychopathology.
Air pollution is the presence of harmful particles, gases, and other substances in the air at concentrations that may damage human health or the environment. These particles can take several different forms. For example, some particulate matter has a diameter of ten micrometers or smaller, allowing it to be easily inhaled into the respiratory system. Coarse particles usually originate from road dust, construction, agriculture, tire and brake wear, and natural sources like soil and pollen.
Unlike particulate matter, nitrogen dioxide is a gas rather than a particle. It is commonly produced by combustion processes, particularly emissions from motor vehicles, power plants, and heating systems. Nitrogen oxides are a broad group of reactive gases that mainly include nitric oxide and nitrogen dioxide. Exposure to these particles and gases may irritate the airways and is associated with respiratory and cardiovascular health problems.
Study author Sharanpreet Kaur and her colleagues explored the association between prenatal exposure to air pollutants and attention-deficit/hyperactivity disorder in the school population from Tarragona, Spain. Tarragona is a Mediterranean region with high petrochemical activity. It is one of southern Europe’s largest chemical and petrochemical clusters, accounting for roughly one quarter of the country’s chemical production.
The study authors hypothesized that higher prenatal exposure to multiple air pollutants increases the risk of attention-related symptoms in children. They expected that exposure to air pollutants would show a stronger association with general symptoms than with a formal clinical diagnosis. The researchers also anticipated that these associations would be stronger in boys than in girls.
The team analyzed data from a large epidemiological project tracking neurodevelopmental disorders in Tarragona. In the first phase of this study, families of 3,727 children consented to participate in a screening for attention issues. The children fell into two age groups, with some of preschool age and others in later elementary school.
A subset of 781 children participated in a secondary clinical screening phase. Researchers excluded children with an autism diagnosis to ensure the data focused solely on attention disorders. In this final group, 174 children were formally diagnosed with attention-deficit/hyperactivity disorder, while 549 children were confirmed to not have the condition.
The authors assessed maternal exposure to air pollutants during pregnancy by asking parents about their residential history. They paired this information with data estimating exposure to traffic-related air pollutants at those specific home addresses. This allowed the researchers to estimate each mother’s exposure to different air pollutants during each distinct trimester of pregnancy.
The results showed that higher prenatal exposures to particulate matter and nitrogen gases were associated with increased teacher-reported attention symptoms in the group of school-age children. However, the data revealed no association between prenatal exposure to air pollutants and the likelihood of being formally diagnosed with any presentation of the disorder.
Looking at specific stages of pregnancy, the results indicated that exposure to air pollutants during early gestation was associated with higher inattentive symptoms. Exposure to particulate matter and nitrogen gases during the first two trimesters was linked to increased inattention as the children grew. This association was noticeably stronger in boys than in girls.
“Our findings suggest that even modest increases in ADHD symptoms may reflect subtle neurodevelopmental effects of prenatal air pollution exposure,” the study authors concluded. “These results highlight early gestation as a vulnerable period and the need for further research on long-term impacts.”
The study contributes to the scientific understanding of environmental risk factors for neurodevelopmental disorders. However, it should be noted that the associations between air pollution exposure and symptom severity were modest in magnitude. Additionally, the observational design of the study does not allow any direct cause-and-effect conclusions to be drawn from the results.
The paper, “Prenatal Exposure to Air Pollution and Risk for Attention-Deficit/hyperactivity Disorder in Children,” was authored by Sharanpreet Kaur, Josefa Canals-Sans, Paula Morales-Hidalgo, Mònica Guxens, Sami Petricola, and Victoria Arija.