Elsevier

Atmospheric Environment

Volume 244, 1 January 2021, 117970
Atmospheric Environment

Long-term exposure to ambient air pollution is associated with elevated low- density lipoprotein cholesterol level

https://doi.org/10.1016/j.atmosenv.2020.117970Get rights and content

Highlights

  • Pollutant exposure to PM2.5, PM10, SO2, NO2, and CO were all positively associated with increased LDL-C level.

  • Increased O3 exposure showed a significant beneficial effect on LDL-C level.

  • More physical activity decreased the effect of air pollution exposure on LDL-C level.

  • Higher WBC counts, representative of in vitro inflammation, increased the effect of air pollution exposure on LDL-C level.

Abstract

Low-density lipoprotein cholesterol (LDL-C) is an important indicator to assess atherosclerosis risk, and air pollution might increase the risk of cardiovascular disease by elevating the LDL-C level. To date, there is no consensus about the associations between exposures to different air pollutants and LDL-C status. In this study, we explored the associations between long-term air pollution exposure and LDL-C status based on a cohort in Northeast China. We found that long-term air pollutant exposure (measured in 10-μg/m3 increments) to PM2.5 (odds ratio [OR] = 2.16, 95% confidence interval [CI]: 1.53–3.04), PM10 (OR = 1.39, 95% CI: 1.12–1.72), SO2 (OR = 1.54, 95% CI: 1.28–1.86), NO2 (OR = 1.44, 95% CI: 1.23–1.67), and CO (OR = 1.02, 95% CI: 101–1.03) were positively associated with elevated LDL-C level. Of all pollutants, PM2.5 had the largest effect on LDL-C level. Increased O3 exposure (OR = 0.66, 95% CI: 0.57–0.76) had a beneficial effect on LDL-C level. Interaction effects of air pollution and physical activity, as well as white blood cell counts, on LDL-C level were found. Effects of air pollution on triglycerides and high-density lipoprotein cholesterol were not significant, and effects of air pollution on total cholesterol were weaker than those on LDL-C. This study provides evidence for the effect of air pollution on LDL-C level, as well as the prevention of atherosclerosis risk.

Introduction

Low-density lipoprotein particles contain approximately 80% of blood lipids and are the main vehicles for transporting cholesterol to tissues outside of the liver. Low-density lipoprotein cholesterol (LDL-C), which is the major lipoprotein in fasting plasma, accounts for approximately two-thirds of plasma lipoprotein. Previous studies proved that LDL-C is an important indicator to assess individual risk of atherosclerosis, as well as coronary heart diseases (Won KB et al., 2019). Increased blood LDL-C will deposit in the arterial wall of heart and brain vessels, which gradually form atherosclerotic plaques and finally cause disabling and fatal severe diseases such as stroke and peripheral artery disease (Zhao Y et al., 2020).

According to the Chinese National Nutrition and Health Survey report in 2014 (Zhang M et al., 2018), the prevalence of high LDL-C (>4.1 mmol/L) was more than three times the rate of 10 years before (2.5% vs. 8.1%), and over 74.5% of adults with a high risk of atherosclerotic cardiovascular disease did not reach an optimal LDL-C level (<2.6 mmol/L). In addition to old age, obesity, and high energy (calorie) intake, ambient air pollution exposure has been proposed as a potential risk factor for increased LDL-C (An Z et al., 2018; Lawal AO. 2017), and air pollution exposure might increase the risk of cardiovascular disease by elevating the LDL-C level (Li J et al., 2019). To date, there is no consensus on the associations between exposures to different air pollutants and LDL-C status. Air pollution has been a severe environmental problem in Northeast China due to fuels used for indoor heating during the cold season and high levels of economic development and traffic growth in the past 10 years (Chang Q et al., 2020); the trend of increasing air pollution has occurred simultaneously with the trend of increasing prevalence of elevated LDL-C and other cardiovascular diseases in North China.

Because of these recent trends, it is of great significance for public health to explore the associations between ambient air pollution exposure and LDL-C level. In this study, we aimed to examine the relationship between long-term air pollution exposure and elevated LDL-C level based on a large prospective cohort study in Northeast China, which might provide more evidence for the effects of air pollution on the risk of hyperlipemia, as well as cardiovascular diseases.

Section snippets

Study population

This study was based on the Northeast Natural Cohort Study (NNCS) of China, which is supported by the national K&D project of China. NNCS is a large, prospective, dynamic cohort study launched in 2017 that focuses on major chronic diseases and risk factors in a variety of populations, including maternal-fetal populations, children, and adults living in Northeast China (Liaoning, Heilongjiang, and Jilin Provinces and inner Mongolia). Different types of one-on-one detailed questionnaire surveys,

Characteristics of participants

Among the 9959 participants available to be analyzed, 16.4% (n = 1401; mean, 3.18 mmol/L) were classified as having an elevated LDL-C level, 12.2% (n = 1212; mean, 1.39 mmol/L) were classified as having a low HDL-C level, 17.2% (n = 1713; mean, 1.64 mmol/L) were classified as having an elevated TG level, and 17% (n = 1695; mean, 5.25 mmol/L) were classified as having an elevated TC level. Characteristics of participants according to LDL-C status are displayed in Table 1. Participants with an

Major findings of this study

In this study, we explored the associations between long-term ambient air pollution exposure and elevated LDL-C level based on a natural cohort study in Northeast China for the first time. Pollutant exposure to PM2.5, PM10, SO2, NO2, and CO were all positively associated with increased LDL-C level, and the effect of PM2.5 was the largest, followed by SO2, NO2, and PM10. Increased O3 exposure showed a significant beneficial effect on LDL-C level. Generalized linear regression ranforced the

Conclusion

Our study demonstrated significant associations between long term air pollution exposure and LDL-C level. We recommend future studies to further explore the associations between air pollution and LDL-C level, as well as the functional role of LDL-C in air pollution and atherosclerosis risk.

Funding

This work was supported by the National Key R&D Project of China (grant number 2017YFC0907401, 2017) and 345 Talent Project of Shengjing Hospital of China Medical University.

Ethics approval and consent to participate

The protocol of this study was approved by the Institutional Review Board of Shengjing Hospital of China Medical University in 2017(No.2017PS190K).

CRediT authorship contribution statement

Zhang Hehua: Software, Data curation, Writing - review & editing. Zhao Yuhong: Conceptualization, Methodology, Investigation, Validation.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

We thank the kind cooperation of participants jointed the cohort and the hard work of all team worker of the cohort. We thank the Bureau of Meteorology and the Environmental Protection Bureau for providing original data of daily pollutant concentrations.

References (32)

Cited by (6)

  • Associations between long term exposures to outdoor air pollution and indoor solid fuel use and depression in China

    2022, Journal of Environmental Management
    Citation Excerpt :

    This cross-sectional study was based on the Northeast Cohort Study of China (NEC-Biobank), which started from January 1, 2018 and covering over 100,000 participants from four provinces in Northeast China (Liaoning, Jilin, Heilongjiang and Inner Mongolia), face to face interview were conducted to collection information of questionnaire, physical and biochemistry test as well as biospecimen retention. Detailed description of the cohort can be found elsewhere (Hehua et al., 2021; Zhang and Zhao, 2020). Participants in this study were aged over 18 years old with no history of depression or other mental diseases; they came from three cities (Shenyang, Dalian and Hinggan League) and completed information on the following categories: age, race, education level, weight, height, family income, smoking and drinking behavior, physical activity, presence of cardiac diseases, hypertension and diabetes, detailed address, indoor solid fuel use, cooking behavior, and kitchen ventilator use.

  • Cohort Profile: The Northeast China Biobank (NEC-Biobank)

    2023, International Journal of Epidemiology
View full text