The air we breathe could determine the way our brain develops. A recent study, published in PLOS One found that high levels of exposure to traffic-related air pollution (TRAP) in early childhood resulted in structural changes in the brain by age 12. Carried out by the Cincinnati Children’s Hospital Medical Cente, the study revealed a loss of cortical thickness and gray matter volume in children with high TRAP exposure when compared to children exposed to lower levels of pollution. 
These team picked their participants from the Cincinnati Childhood Allergy and Air Pollution Study, which constituted infants below the age of six months. The participants included children with both high and low exposure to TRAP in the first year of their life. TRAP levels were estimated by evaluating the air quality at different sites in the city. Regular examinations of the children were conducted with clinic visits at ages 1, 2, 3, 4, 7 and 12. The final readings were based on magnetic resonance imaging of the anatomical brain images of 147 children, aged 12.
The results revealed that in children with high levels of TRAP exposure there was a regional reduction of gray matter volume and cortical thickness. The gray matter in the brain is associated with sensory perception and motor control, while cortical thickness is the depth of the outer gray matter. There was a decrease of 3-4 percent in the frontal lobe, parietal lobes, and the cerebellum. These regions of the brain are formed early in childhood and are vulnerable to damage in this critical period.