Study links air pollution to childhood obesity through impulse control

First year of life is key window for neurotoxic effects on self-control

The study, published Monday in a peer-reviewed journal, is described by its authors as the first to identify inhibitory control — the ability to regulate impulses — as a potential mechanism linking PM2.5 exposure to childhood obesity. Previous research had established that PM2.5 has obesogenic properties that can disrupt metabolism, but the neurodevelopmental pathway had not been explored.

PM2.5 is a pollutant composed of microscopic solid or liquid particles suspended in air. Common manmade sources include traffic emissions and the burning of fossil fuels. It is classified as a probable carcinogen and has been linked to a range of health problems including dementia and strokes. About 42% of American adults were estimated to be obese in 2018, according to earlier data.

Jamil Lane, a co-author with Mount Sinai’s Icahn School of Medicine, said that much obesity research focuses on diet and physical activity and may not include environmental exposures such as air pollution.

“Our study is novel in that we are showing that high levels of air pollution early in life may cause more difficulty with self-regulation, which contributes to weight gain,” Lane said.

Bob Wright, a study co-author and environmental epidemiologist at Mount Sinai, said the researchers wondered whether PM2.5’s neurotoxic effects and obesity were “part of the same processes.” The team examined data from 434 children enrolled in a longitudinal health study in Mexico City, born largely between 2007 and 2008. They modeled ambient PM2.5 levels during pregnancy and during the children’s first year of life, which Lane described as a “very sensitive window” for brain development. The children were later assessed for impulsivity and obesity measures.

The group with the highest levels of PM2.5 exposure showed a pattern of high impulsivity, reflecting significant deficits in inhibitory control.

“Our study shows that greater early exposure to PM2.5 in the first year of life is associated with alterations in inhibitory control function in childhood,” the study’s authors wrote. “The effect is likely due to altered eating behaviors related to inhibitory control that are programmed early in life.”

The study acknowledges limitations, including a small population and limited covariates. Cecilia Moura, a clean transportation scientist with the Union of Concerned Scientists who was not involved in the research, said the study was sound and its novel findings “indicate there is sufficient evidence supporting the correlation to motivate policies and regulations that mitigate exposure to PM2.5.”

Moura noted that individuals can take steps to protect themselves and their children. Home HEPA air filtration systems are effective at removing PM2.5, as are furnace filters rated MERV 13 or higher. DIY filtration systems using a box fan, cardboard, tape, and pleated air filters have also been shown to reduce particulate matter. The authors advised parents to avoid high-traffic areas when possible and to stay indoors during heavy wildfire smoke events.

But Wright cautioned that individuals cannot fully protect themselves, underscoring the need for policy solutions.

“There is not going to be change if people are not aware and lobbying for it, but policy change takes a long time and there are things we can do to protect ourselves,” Wright said.