Exposure to common air pollution may cause childhood obesity because it affects children’s ability to control impulses, according to new first-of-its-kind peer-reviewed research.
PM2.5 and Obesity Connection
Particulate matter 2.5 (PM2.5), a neurotoxin, has been linked to obesity. Researchers at Mt Sinai say they have identified impulse control as a potential pathway for the first time. The study found that babies exposed to higher levels of PM2.5 during their first year were more likely to develop difficulties with controlling impulses later in childhood. These behavioral changes were then linked to higher body fat and higher BMI in children aged four to eight.
“A lot of the obesity research primarily focuses on diet and physical activity, and may not include environmental exposures, including air pollution,” said Jamil Lane, a co-author with Mt Sinai’s Icahn School of Medicine. “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.”
Understanding PM2.5
PM2.5 consists of microscopic solid or liquid particles suspended in the air. Common manmade sources include traffic emissions and burning fossil fuels. It is considered a probable carcinogen and is linked to health problems from dementia to strokes. Previous research has shown PM2.5 has obesogenic properties that can disrupt metabolism and is associated with weight gain. About 42% of American adults were estimated to be obese in 2018.
It is well-established that poor inhibitory control is linked to obesity. Bob Wright, a study co-author and environmental epidemiologist at Mt Sinai, said the authors wondered if the substance’s neurotoxic effects and obesity were “part of the same processes.”
Study Details and Findings
Researchers analyzed data from 434 children born largely between 2007 and 2008 in Mexico City who are part of a longitudinal health study. They modeled ambient PM2.5 levels during pregnancy and the children’s first year of life, which Lane called a “very sensitive window” for brain development. Children were later assessed for impulsivity and obesity measures. The group with the highest 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 authors wrote. “The effect is likely due to altered eating behaviors related to inhibitory control that are programmed early in life.”
Limitations and Expert Commentary
The study acknowledges limitations, including a small population size and limited covariates. Cecilia Moura, a clean transportation scientist with the Union of Concerned Scientists not involved in the study, said the research was sound and the novel findings “indicate there is sufficient evidence supporting the correlation to motivate policies and regulations that mitigate exposure to PM2.5.”
Protective Measures and Policy Needs
People can take steps to protect themselves and their children. Home HEPA air filtration systems are effective at removing PM2.5, while furnace filters rated at MERV 13 or higher also capture much of the substance. DIY filtration systems using a box fan, cardboard, tape, and pleated air filters have been shown effective at reducing particulate matter. The authors advised parents to avoid high congestion areas and stay indoors during heavy wildfire smoke.
However, individuals cannot fully protect themselves, and the findings highlight the need for policy solutions and raising awareness, Wright said. “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.”
