A team of Spanish researchers has found that air pollution from traffic is hurting kids’ intelligence. And, in their study, the damage happened within a critical time window for the development of processes that guide planning, focus, memory, and multitasking.
Another recent study conducted in New York City reported that a pollutant children were exposed to in the womb was also harmful to them later. The study indicated the pollutant, polycyclic aromatic hydrocarbons (PAHs), caused physical changes in the children’s brain wiring.
That, in turn, was correlated with slower cognitive processing, attention deficit, and hyperactivity. The combination made them very impulsive, he says, which could cause poor decision-making.
Together, the studies are further indication that the health effects of air pollution go beyond the respiratory problems that are already well documented. Early studies in Mexico City had already connected air pollution to brain inflammation found in diseases such as multiple sclerosis.
The Spanish researchers found that children in Barcelona attending schools in high pollution areas had less cognitive development over the course of a year than children in less-polluted areas. The study included 7- to 10-year-olds at 39 schools. They were given computerized tests that measured changes in their working memory and attention spans.
Lead author Jordi Sunyer, co-director of the Centre for Research in Environmental Epidemiology, says that air pollution could lead to an increase in collective “school failure.”
“The implications are probably not noticeable at an individual level, but at the community level the cognitive, functional impact may have a social impact,” he says. Previous studies on the mental impact of lead in gasoline produced similar results.
Sunyer says the Spanish study is more evidence that should compel environmental policy makers to take action. Potential impacts could include controlling traffic better and reducing fine particles from diesel engines in urban areas.
“For the average person, it’s important to avoid commuting to the schools by car,” he adds. “If possible, bike or walk.” If you can't do either of those, park your car at least 100 meters from the school or turn off the engine in front of the school while waiting for your child. Sunyer also urges that school buses should always have a particulate filter that is checked to make sure it’s working.
Another environmental expert agrees the “take home message” is a warning to parents that respiratory problems may be the tip of the iceberg.
Serap Erdal, PhD, an associate professor of environmental and occupational health sciences at the University of Illinois at Chicago, says the Barcelona study is significant because it does look at children at a “crucial” age for brain development.
She also notes the study occurred during a short time period and in a specific geographic region. But even with its limitations, the study will generate interest in further research that could influence regulators and further warn the public, Erdal believes.
“For those parents whose homes are near highways, there is an elevated health risk,” she says. “We already knew that.” But this study, with its focus on young, cognitively vulnerable children, could be, and should be, a catalyst for community activism by the people affected in urban areas, Erdal adds.
In the New York City study, more than 600 expectant mothers carried detector backpacks that measured their exposure to PAHs. These chemicals come from common pollutants such as vehicle exhaust, power plant emissions, and cigarette smoke. The women’s children were later tested for exposure and given cognitive and behavioral tests.
The brain damage measured didn’t just occur prenatally. Postnatal PAH exposure measured at age 5 also indicated an adverse effect in a different area of the brain.
“It’s a double hit,” lead author Bradley Peterson, MD, director of the Institute for the Developing Mind at The Saban Research Institute of Children’s Hospital Los Angeles, told the Los Angeles Times. “They have the abnormality from prenatal life throughout the left hemisphere and then on top of that they have this bilateral front hit from exposures around age 5.”
The damage before the children were born, and then later to the prefrontal bilateral region of their brains, disrupted the development of white matter. White matter affects how the brain learns and functions. It’s been called the “subway of the brain,” connecting regions of grey matter so that the brain operates efficiently.
From Mexico City to Beijing, air pollution and its impact on health has been thoroughly studied. Pollution can harm lung tissue and, in turn, weaken our body’s defenses against harmful microbes and large particles like dust and pollen. It can also lead to heart problems. But research over the last decade has suggested that brain development is affected as well. And, it’s not just in kids. A study of 19,000 nurses reported a greater cognitive decline among older women exposed to high levels of particulates. Yet another study involving men had similar results.
April 02, 2015
Christopher Nystuen, MD, MBA