A study from researchers at the Columbia Center for Children's Environmental Health (CCCEH) showed that prenatal exposure to environmental neurotoxic and carcinogenic combustion-related air pollutants (i.e., polycyclic aromatic hydrocarbons [PAH]), in addition to socioeconomic disadvantage (i.e., poverty) and its associated psychosocial stress, increase the risk of ADHD symptoms and behavior in children.