# The association between long-term outdoor air pollution exposure and Chinese visceral adiposity index: A nationwide study of middle-aged and older adults

## TL;DR

This study shows that long-term exposure to air pollution increases visceral fat in middle-aged and older Chinese adults, especially in men and smokers.

## Contribution

First nationwide study to link outdoor air pollution with visceral adiposity in Chinese adults.

## Key findings

- All tested pollutants (PM2.5, PM10, NO2, O3, SO2) showed significant positive associations with visceral adiposity.
- Males and active smokers had the strongest associations, with PM2.5 and NO2 being the main contributors.
- Dose-response relationships were observed across all pollutants.

## Abstract

Outdoor air pollutants, particularly particulate matter (PM) and nitrogen dioxide (NO2), have been closely linked to diabetes mellitus, other metabolic disorders, and cardiovascular diseases. Visceral adiposity, a common high-risk factor for these conditions, may mediate the impact of air pollution on disease development. However, the potential role of outdoor air pollution on visceral adiposity remains unclear, especially in the Asian population and in older adults (> 60 years). Given the high levels of air pollution and the rising prevalence of visceral obesity in China, this study investigated whether there is a linear and/or non-linear association between the Chinese Visceral Adiposity Index (cVAI) and exposure to individual and combined air pollutants in 7,552 participants aged ≥ 45 years in China. Data on air pollutants were acquired from the ChinaHighAirPollution dataset. These included PM with an aerodynamic diameter ≤ 2.5 μm (PM2.5), PM10, NO2, ozone (O3), and sulfur dioxide (SO2). Our results demonstrate that exposure to all of these pollutants (PM2.5, PM10, NO2, O3, and SO2) was significantly and positively associated with the cVAI, with dose-response relationships observed in trends test across pollutants. In subgroup anslysis, the associations were particularly pronounced in men and active smokers. Specifically, smokers in the highest quartile of PM2.5 exposure had a β coefficient of 16.89 (95%CI:11.00, 22.78), while males had a β coefficient of 14.38 (95%CI:9.68, 19.07). NO2 and PM2.5 were identified as the primary contributors to the total effect of outdoor air pollution exposure. In conclusion, this study is the first to reveal that outdoor air pollutants, particularly PM2.5 and NO2, are significantly associated with increased visceral adiposity in middle-aged and older Chinese adults. Males and active smokers could be high risk groups, when compared with females and non-smokers. This study highlights an urgent need for public health policies mitigating visceral obesity through the reduction of outdoor air pollution exposure.