Air Pollution Linked with Overweight and Obesity in Childhood

Air Pollution Linked with Overweight and Obesity in Childhood

When we breathe in polluted air, it irritates our respiratory system and we may experience breathing difficulties. In the long run, exposure contaminated air and smoke produced by industries and vehicles can lead to decreased lung function, diseases such as asthma, bronchitis, emphysema, and possibly other cardiovascular and respiratory diseases, as well as cancer. Now another health problem might be added to the list—childhood obesity.

Impacts of Obesity in Children

Looking at the many severe diseases linked to air pollution, obesity seems a little insignificant. However, this condition should not be overlooked.

Obesity affects up to 15-20 percent of children worldwide. Aside from the various health hazards linked to obesity such as diabetes, high cholesterol, asthma, sleep apnea, gallstones, and cardiovascular diseases. Overweight and obesity also affect the psychological being of children.

Several studies reveal that childhood obesity can lead to low self-esteem, anxiety, and depression. This is commonly due to social exclusion, negative stereotypes, and bullying. In fact, some experts described being overweight as “one of the most stigmatizing and least socially acceptable conditions in childhood.”

Obesity and Air Pollution

Researchers at the Barcelona Institute for Global Health (ISGlobal) claimed that exposure to air pollution, especially at school, might be liked with a higher risk of overweight and obesity during childhood. In a study published in Environment International, researchers investigated 2,660 children ages 7-10 years old from 39 schools in Barcelona under the BREATHE project.

The team collected data on the children’s height and weight to calculate their body mass index (BMI). They also assessed the levels of pollution in the school areas. Among the pollutants they measured are nitrogen dioxide, elemental carbon, particle matter, and ultrafine particles. They examined the pollutants twice; during a week in summer and another week in winter.

Jeroen de Bont, a researcher at ISGlobal and first author of the study concluded that children exposed with medium to high levels of the measured air pollutants had “a higher risk of obesity and overweight as compared to those exposed to lower levels.”

It was also revealed that many children were exposed to air pollution levels above the World Health Organisation (WHO) recommended levels. To be specific, more than 75 percent were exposed to unsafe levels of particle matter. While more than 50 percent were exposed to the above-recommended level of nitrogen dioxide.

Study Limitations

The researchers, however, highlighted that their study has limitations. One of the reasons is because their analysis was done with only estimates of exposure levels. Martine Vrijheid, ISGlobal researcher and study coordinator explained:

“The study has however some limitations, which means that the results are to be cautiously interpreted. Being a cross-sectional study, we only have data at one time-point, and we do not have enough data to establish the nature of the association. To draw more solid conclusions, we need new longitudinal studies that follow the study participants over time.”

But how can air pollution possibly affect obesity? Researchers explained the underlying mechanisms on the idea. Previous animal studies reveal that air pollution can induce insulin resistance, oxidative stress, and systemic inflammation. These are known factors that contribute to obesity.

In the study in particular researchers identified that ultrafine particles were the pollutants that had the most effect in increasing the risk of overweight or obesity. “This may be explained by the fact that the ultrafine fraction of the particles deposit in greater number and deeper into the lungs than do large-size particles, having more capacity to reach the circulation and induce oxidative stress and inflammation,” the researchers wrote.