The relationship between long-term exposure to environmental NO2 and HDL levels among middle-aged and older adults in China

Abstract Background In recent years, an increasing number of studies have confirmed that air pollution mixtures can lead to abnormal levels of lipid proteins in the body. With the continuous deepening of research, the specific effects of different components in air pollution mixtures on human health have gradually begun to be explored. Nitrogen dioxide (NO 2 ), as an essential component of air pollutants, hurts human health. Normal levels of high-density lipoprotein (HDL) play a crucial role in preventing cardiovascular diseases. However, the effect of environmental NO 2 on HDL levels has yet to be further studied. Our study aims to explore the potential association between environmental NO 2 exposure and HDL levels in middle-aged and elderly populations aged 45 and above in China. Methods Our research subjects are the third-wave China Health and Retirement Longitudinal Study (CHARLS) participants. This cross-sectional study analyzed the personal data of 12519 participants aged 45 and above with venous blood samples. The participants' high-quality and high-resolution NO 2 exposure concentration data were obtained from the Chinese Air Pollutants (CHAP) dataset, and the HDL levels were obtained from the analysis results of venous blood samples. Multiple linear regression analysis, supplemented by subgroup analysis, was used to explore the correlation between NO 2 exposure concentration and HDL levels. Results This cross-sectional study found a negative correlation between long-term exposure to air NO 2 and HDL levels. The observed correlation between air NO 2 and HDL levels indicates that middle-aged and older adults living in areas with high NO 2 concentrations exhibit a decrease in HDL levels (Beta: -0.132; 95% CI: (-0.153, -0.111); P < 0.0001). This association still exists after considering various potential confounding factors (Beta=-0.103, 95% CI: -0.124, -0.083, p < 0.0001). Conclusions Our research results show a significant negative correlation between long-term exposure to high concentrations of NO 2 and HDL levels in the middle-aged and elderly population in China.