Add bad air to risk factors associated with gaining weight, or at least in certain women.

A new study out of the University of Michigan suggests that exposure to air pollution is added to one of the many risk factors associated with women putting on unwanted weight, particularly in their late 40s and early 50s. 

Their findings reveal that long-term exposure to air pollutants, specifically fine particulate matter, nitrogen dioxide, and ozone, led to a rise in a woman’s body weight, body mass, waist circumference, and body fat.

Obesity has been a global public health issue and has tripled in prevalence over the past years. It has been linked to health consequences such as type 2 diabetes, cardiovascular disease as well as certain cancers.

Prior studies have reported links between exposure to polluted air and obesity. Although, this evidence was limited to children.

Importantly, this is the first study to explore the link between air pollution and body size and composition in midlife women.

Lead author Xin Wang and the team used a dataset involving a total of 1,654 women with an average age of 50 years from diverse ethnic groups. About half the women made up whites and the other half encompassed both black, Chinese, and Japanese women followed up from 2000 to 2008. Yearly high-resolution air pollution exposure data were taken and this was determined by linking residential addresses with hybrid estimates of the level of air pollutants. Then a periodic measure of body size and composition was taken to examine associations with air pollution.

One other factor the researchers worked to explore was whether engaging in high physical activity had any effect on the association.

After a follow-up of 9 years, the study authors found that exposure to polluted air was indeed linked with negative change outcomes in body composition measures. Particularly particulate matter and nitrogen dioxide were greatly linked with fat mass and proportion fat mass and lower lean mass among midlife women. This gave roughly 4.6 percent higher body fat, translating to 2.6 pounds.

However, Wang and the team found that the impact was reduced among those with higher physical activity levels

The researchers note that the findings most likely do not apply to everyone as the data only focused on middle-aged women from a certain community (I.e. women in the United States or other Asian ethnic groups). So as such shouldn’t be generalized to men and other ages and regions. 

Above all, this study adds to the growing body of evidence that chronic exposure to air pollution may add to midlife women’s obesity through its effect on fat and lean mass changes. The study authors also go further to highlight how necessary it is to increase the level of physical activity as it is seen to go a long way in slashing the hostile effects of air pollution on women’s body composition.

Read the full paper in the journal Diabetes Care.

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