The double whammy of poverty and exposure to air pollution can lower a child's IQ, according to researchers at the Columbia Center for Children's Environmental Health at the Mailman School of Public Health.
A new study, published in Neurotoxicology and Teratology, found that kids born to moms who experienced both economic hardship during pregnancy and exposure to air pollution (specifically polycyclic aromatic hydrocarbons, or PAH), had lower IQ scores at age 5 than children exposed to fewer pollutants and born to wealthier mothers. PAH commonly comes from emissions from cars, oil, coal-burning for home heating and electricity, and tobacco smoke.
The study focused on 276 mother-child pairs in New York City from pregnancy to early childhood, and researchers examined cord blood to measure exposure to pollutants. They found that at age 7, among children of mothers who experienced financial hardship, those who also experienced high levels of pollution scored lower in tests of perceptual reasoning, working memory and other IQ indicators.
Kids from higher-income families who were exposed to pollution didn't have significantly lower IQ results.
The same researchers previously found that 7-year-olds exposed to high levels of PAH had developmental delays at age 3, reduced verbal skills at age 5, and symptoms of anxiety and depression at age 7.
Authors say the findings add to a mounting body of evidence that poverty can increase the adverse effects of toxic "stressors" like pollution, even in utero and early childhood.
"The findings support policy interventions to reduce air pollution exposure in urban areas as well as programs to screen women early in pregnancy to identify those in need of psychological or material support," said Frederica Perera, senior author of the paper.
According to the Columbia Center for Children's Environmental Health, or CCCEH, parents can lower indoor air pollution at home by not smoking near children and not letting others smoke near children, not charring or blackening food, using a kitchen fan when cooking, and limiting the use of burning candles and incense.
Outdoor air pollution is much harder to control, especially in urban areas where much of it comes from heavy traffic. Diesel trucks and buses are the worst polluters, according to CCCEH, because without certain emission controls they put out 50 times more pollution than gasoline vehicles.
Burning diesel fuel releases black carbon particles into the air, which can't be filtered by the body and gets deep into the lungs. CCCEH measured indoor pollution and found that the same amount of black carbon was found inside the home as outside — which means that city dwellers, including kids, breathe bus and truck pollution indoors, too.