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

Air pollution has been closely linked to diabetes, metabolic disorders,
and cardiovascular diseases; visceral adiposity is a common high-risk
factor for these conditions. However, the potential role of air pollution
on visceral adiposity remains unclear. In this study, we investigated the
association between exposure to multiple air pollutants and visceral
adiposity using the Chinese visceral adiposity index (cVAI) in middle-aged
(45 - 60 years) and older (> 60 years) Chinese adults. We conducted
a cross-sectional study using data from 7,552 participants aged ≥45 years
from the 2015 China Health and Retirement Longitudinal Study 2015. Data
related to air pollution exposure levels, including particulate matter
with an aerodynamic diameters ≤ 2.5 μm (PM2.5), particulate matter with an
aerodynamic diameters ≤ 10 μm (PM10), nitrogen dioxide (NO2), ozone (O3),
and sulfur dioxide (SO2), were acquired from the ChinaHighAirPollution
dataset. Restricted cubic spline analysis was then used to investigate
potential non-linear associations. Weighted quantile sum (WQS) regression
was also used to address co-exposure to multiple pollutants and identify
the relative contributions of each pollutant. Compared to the lowest
quantile, exposure to the highest quartile levels of PM2.5, PM10, NO2, O3,
and SO2 was associated with a significant increase in cVAI (all p for
trend <0.0001). Males and smokers exhibited stronger associations
between air pollutant exposure and cVAI(p for interaction < 0.05).
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), indicating significantly higher risks of
increased visceral adiposity in these groups. WQS analysis identified NO2
and PM2.5 as the primary contributors to increased cVAI. This study is the
first to reveal that air pollution, particularly PM2.5 and NO2, was
significantly associated with increased visceral adiposity in middle-aged
and older Chinese adults, especially for high-risk groups, such as males
and smokers. It highlights the urgent need for public health policies to
reduce air pollution exposure to mitigate the risk of visceral adiposity
and its associated metabolic disorders.