Exposure to Air Pollution May be a Factor in Obesity in Women
Air pollution in Delhi, India.

New evidence that exposure to air pollution can potentially contribute to obesity in women has emerged from a study by the University of Michigan

“Women in their late 40s and early 50s exposed long-term to air pollution—specifically, higher levels of fine particles, nitrogen dioxide and ozone—saw increases in their body size and composition measures,” said Xin Wang, epidemiology research investigator at the University of Michigan School of Public Health and the study’s first author. 

By cross-referencing the residential addresses of the 1,654 US women participating in the study with hybrid air pollutant concentration estimates from 2000 to 2008, the data showed exposure to air pollution was linked with higher body fat, body mass index, and lower lean mass.

But it is not all bad news. The study found that while body fat increased by 4.5%, high levels of physical activity were an effective way to mitigate and offset the effects of air pollution exposure.

Pollution and obesity: a growing link 

With an unprecedented increase in body weight issues worldwide over the last decades, numerous studies have sought to understand the complex and varied causes of obesity – and this is not the first to explore the link to air pollution.

In 2019, researchers at the University of California at Santa Barbara published the first study estimating the causal effect of air pollution on body weight based on data from 13,226 adults in China from 1989-2011. 

This period of study is unique for its historical backdrop. Across the years of the study, China’s economic explosion contributed to a rise in fine particulate matter concentration by 70%. During this time, China’s average BMI increased by 11%, while overweight and obesity rates increased from 8.57% to 32.83% and 0.48% to 4.9% respectively.

“Our study suggests that the cost of air pollution on overweight and obesity is non-trivial,” the authors state. “Although the effect’s magnitude is smaller than studies focused on other economic [and socioeconomic] variables, it is in the same order of scale.”

The International Journal of Obesity also highlighted the potential effects of ambient air pollution on child obesity development but noted evidence is still scarce.

“Early life exposure to air pollution may be associated with a small increase in the risk of developing overweight and obesity in childhood, and this association may be exacerbated in the most deprived areas,” the journal notes. “Even these small associations are of potential global health importance.”

The most striking results came from a study conducted by the Lung Care Foundation and Pulmocare Research and Education in India. The results found that while 39.8% of the children in Dehli, one of the world’s most polluted cities, were obese or overweight, this was true for only 16.4% of children in Kottayam and Mysuru, cities with significantly better air quality.

As studies continue to deepen our understanding of the toxic effects of fine particulate matter (PM2.5) on human health, the silent threat posed by polluted air has revealed itself to be more multifaceted than previously known – and extremely deadly.  

With 99% of the global population breathing air beyond the World Health Organization’s recommended quality limits, an estimated nine million deaths are caused by modern air pollution sources every year. 

New evidence of the adverse effects of air pollution is emerging at a rapid clip, but despite the economic and health implications, progress on the policy front remains slow.

Image Credits: Ella Ivanescu/ Unsplash, Wikimedia Commons: Prami.ap90.

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