Previous research has shown association between exposure to long-term air pollution and adverse lipid profiles. Fewer studies have been performed using metabolomics, which identify and quantify small molecules to represent an organism’s metabolic state. A metabolic signature in the blood associated with ambient air pollution exposure is plausible given some ambient air pollutants (ultrafine particles and gaseous air pollution) have been reported to enter the bloodstream directly from the lungs. Most research in this area has focused on adulthood, and little evidence is available in younger ages. This study aims to assess the metabolomic signature of air pollution in childhood.