Researchers found it while studying umbilical cord blood of  the children at New York City. The change was noticed in the gene called ACSL3 linked with the prenatal exposure to polycyclic aromatic hydrocarbons(PAHs) which may result in epigenetic changes(genetic alterations) by reprogramming the genes in key developmental periods but the disease may develop later on.

By examining the mothers exposure to PAHs during pregnancy and analyzing its effects on the samples of umbilical white blood cell from 56 children to study epigenetic alterations. A significant relation is found in ACSL3 gene of the lung and maternal PAH exposure. The children prior to age 5 were  reported with ACSL3 in the parental report of asthma symptoms.

The latest research has complemented the old one hence provided a significant clue to detect environmentally related asthma in children born to the mothers live in heavy traffic or chemically polluted areas.