Recent study explored effect of pollution on IQ levels. Researchers indicated that prenatal exposure to urban ail pollutants can lower IQ of children. Motor vehicles release polycyclic aromatic hydrocarbons or PAHs in the air. These chemicals are produced from the burning of coal, diesel, oil and gas, or other organic substances such as tobacco.

Research team at the Columbia Center for Children''s Environmental Health (CCCEH) at the Mailman School of Public Health found that fetal exposure to high levels of PAHs led to lower IQ in later life.

Researchers reached the findings after analyzing data collected from
249 children and their mothers. The children were followed from utero to five years of age.

PAHs exposure was measured through air monitors wore by mothers during pregnancy. Mothers also filled questionnaires. At the age of five children were given an intelligence test known as the Wechsler Preschool and Primary Scale of the Intelligence. Data analysis revealed that verbal IQ scores of children more exposed to PAHs were
4.31 and 4.67 points lower than those of less exposed children.

Linda Birnbaum, director of NIEHS said: "This is the first study to report an association between PAH exposure and IQ, and it should serve as a warning bell to us all. We need to do more to prevent environmental exposures from harming our children."