Children from urban areas may be at a higher risk of obesity due to high levels of pollution, noise and traffic, according to a study published in the journal Environment International (1). Results showed that it’s not just pollution that increases the risk of obesity: living near fast-food restaurants reinforces the dangers of becoming overweight, but curiously the researchers found no link between childhood obesity and physical exercise.
To date, research looking at the impact of the environment on childhood obesity has been scarce. Keen to understand this connection, a team of researchers from the Barcelona Institute for Global Health and the University Institute for Primary Care Research Jordi Gol investigated the link between childhood obesity and several urban factors, including the density of unhealthy food restaurants, road traffic, air pollution and access to green areas, among others. Between October 2017 and January 2019, 2,213 children between 9 and 12 years old were assessed in terms of body mass index, waist circumference and body fat, as well as consumption of sugary items, physical activity, sleep patterns and well-being.
“Higher levels of air pollution, traffic and noise were associated with higher body mass index and a higher likelihood of the child being overweight or obese,” explained lead author Jeroen de Bont, a researcher at ISGlobal and IDIAP Jordi Gol. In fact, results showed that forty percent of the children were overweight or obese.
Based on these results, the team suggested that air pollution can disrupt vital molecular mechanisms causing an hormonal imbalance and inducing inflammation, inevitably leading to obesity in these children. At the same time, excessive noise can lead to poor sleep and an increase in stress hormones, which are associated with poor physical development and obesity in children.
However, it’s not all about pollution. The researchers also found a strong link between the number of unhealthy fast-food restaurants and the rate of childhood obesity, most likely because this encourages going to these restaurants and consume meals with a high caloric value.
Curiously, there was no connection between physical activity, obesity and the surrounding environment. This came somewhat as a surprise, as it was expected that areas with a well-established transport network and various local shops would encourage people to travel on foot or by bike, increasing physical activity. However, the questionnaire to collect information about physical activity did not consider where the activities took place. “We were able to find out if the children played basketball or football, but not if they cycled in nearby green spaces, for example,” added de Bont.
Finally, the researchers believe socioeconomic status played a role in childhood obesity, but it was not clear yet how. Children living in more deprived areas – often in the city’s outskirts – showed higher rates of obesity despite living in a place with less pollution, road traffic and noise.
Further research is needed to understand this connection better, but many scientists believe that understanding how the environment can influence rates of childhood obesity would support the development of health programmes encouraging better and healthier behaviours in urban areas.
(1) de Bont J, Márquez S, Fernández-Barrés S, Warembourg C, Koch S, Persavento C, Fochs S, Pey N, de Castro M, Fossati S, Nieuwenhuijsen M, Basagaña X, Casas M, Duarte-Salles T, Vrijheid M. Urban environment and obesity and weight-related behaviours in primary school children. Environment International. 155, 2021. https://doi.org/10.1016/j.envint.2021.106700.