Air Pollution & Population Density May Raise Childhood Obesity Risk, Research Finds

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A new study has found that air pollution, smoking and environmental factors such as population density can play a role in childhood obesity. The research comes as scientists begin to gain a deeper understanding of the urban factors and toxins that are the riskiest by looking into all exposures that affect individuals. 

Published in the peer-reviewed journal Environmental Health Perspectives, the study reviews 77 factors during pregnancy and 96 factors during childhood. Scientists found that air pollution, smoking and individuals’ built environment can increase the risk of obesity in children from birth to 11 years of age. 

Of the children studied by the researchers from the University of Southern California (USC) and the Barcelona Institute for Global Health (ISGlobal), 28.8% were considered either overweight or obese. Of the three riskiest factors, air pollution had the highest correlation with body mass index (BMI), followed by smoking during pregnancy. 

Children who live in densely populated areas with fewer parks and less access to public transportation were also more likely to have higher BMI measurements, mainly due to decreased opportunities for physical activity – an indication that individuals’ built environment can trigger higher obesity rates in children as well. 

Scientists additionally analysed common toxic exposures, such as PFAS chemicals, commonly used in non-stick cookware, takeaway containers and stain-resistant furniture coatings, as well as heavy metals, but found inconclusive results. According to the study, blood concentration samples could be impacted by other factors such as the metabolic cycle, making it difficult to determine the effect of toxic exposures. 

The study represents perhaps the first comprehensive analysis of all environmental exposures – the entire exposome. Prior to this, some studies have examined single exposures.  

“To our knowledge, [this is] the first systematic analysis of associations between many environmental exposures and childhood obesity,” the researchers wrote. 

Previous research has shown that breathing polluted air during pregnancy is linked to low birth weights, but this particular exposome-wide study furthers our understanding of the longer-term effects of dirty air exposures, showing that the body can try to play “catch up” after birth, which in turn speeds up weight gain and increases the risk of obesity in childhood. 

Scientists say that there needs to be more research into exposomic factors in order to gain a better understanding about prenatal and childhood development. They say that an exposomic approach, which can link urban factors with outcomes, can have positive implications for policies for preventing the negative consequences of different environments. 

“These results may help to identify targets for prevention and intervention early in life, leading to better science-based regulation of environmental obesogenic exposures,” said the authors. 

Earlier in February, Professor Robert Wright from the Icahn School of Medicine at Mount Sinai said that exploring our environment can empower us to make informed lifestyle changes that will benefit our health the most. 

He pointed to the availability of data sets, thanks to modern technology, that researchers should use to evaluate individuals’ weather patterns, air quality, light exposure and noise levels. This may make it easier for scientists to make associations between how each our surrounding environment and genetics work in combination to produce health effects. 

Lead image courtesy of Deposit Photos.


  • Sally Ho

    Sally Ho is Green Queen's former resident writer and lead reporter. Passionate about the environment, social issues and health, she is always looking into the latest climate stories in Hong Kong and beyond. A long-time vegan, she also hopes to promote healthy and plant-based lifestyle choices in Asia. Sally has a background in Politics and International Relations from her studies at the London School of Economics and Political Science.

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