The study looked at children who were born to non-smoking black and Dominican American women age 18 to 35 from the deprived Washington Heights, Harlem or the South Bronx neighbourhoods in New York.

The children were monitored from the womb through to the age of five with mothers wearing air monitoring equipment and answering questionnaires.

It found prenatal exposure to environmental pollutants known as polycyclic aromatic hydrocarbons (PAHs) can affect a child’s intelligence quotient or IQ.

The findings are from new research by the US-based Columbia Center for Children’s Environmental Health (CCCEH) at the Mailman School of Public Health.

PAHs are chemicals released into the air from the burning of coal, diesel, oil and gas or other organic substances such as tobacco.

Environmental Protection Agency and several private foundations, found that children exposed to high levels of PAHs in New York City had full scale and verbal IQ scores that were 4.31 and 4.67 points lower, respectively than those of less exposed children.

“These findings are of concern because these decreases in IQ could be educationally meaningful in terms of school performance,” says Frederica Perera, professor of environmental health sciences and director of the CCCEH and study lead author.

“The good news is that we have seen a decline in air pollution exposure in our cohort since 1998, testifying to the importance of policies to reduce traffic congestion and other sources of fossil fuel combustion by products.”

The mothers wore personal air monitors during pregnancy to measure exposure

to PAHs and they responded to questionnaires

At five years of age, 249 children were given an intelligence test known as the Wechsler Preschool and Primary Scale of the Intelligence, which provides verbal, performance and full-scale IQ scores.

Of these 140 children were classified as having had a ‘high exposure’ to pollution.

“The decrease in full-scale IQ score among the more exposed children is similar to that seen with low-level lead exposure,” added Dr Perera.

“This finding is of concern because IQ is an important predictor of future academic performance, and PAHs are widespread in urban environments and throughout the world.

“Fortunately, airborne PAH concentrations can be reduced through currently available controls, alternative energy sources and policy interventions.”

Luke Walsh

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