Association of long-term exposure to PM2.5 with blood lipids in the Chinese population: Findings from a longitudinal quasi-experiment

Background: Although epidemiological studies on the effect of chronic fine particulate matter (PM2.5) exposure on lipid disorders have been conducted, it is unclear if improved air quality is associated with beneficial changes in the blood lipid profile. In China, clean air actions introduced in 2013 have rapidly reduced the concentration of ambient PM2.5. Methods: We conducted a change-by-change study, based on two waves (2011 and 2015) of a national survey of the same 5111 Chinese adults before and after implementation of the clean air actions. Long-term PM2.5 exposure was assessed using a state-of-the-art estimator at the city level. Based on the within-individual differences between the two waves, we associated PM2.5 changes with the variations of four lipid biomarkers-triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C)-using a mixed-effects regression model. The robustness and homogeneity of the association were tested via sensitivity analyses. Results: For each 10 mu g/m(3) reduction in PM2.5, LDL-C, and TC decreased by 2.71 (95% confidence interval [CI] 0.10-5.32) and 4.16 (95% CI 1.24-7.08) mg/dL, respectively. There was no significant association with HDL-C or TG. The results were robust among models adjusted for different covariates. PM2.5 was a significant risk factor for dyslipidemia with an adjusted relative risk of 1.21 (95% CI 1.09-1.34). The association between PM2.5 and LDL-C was stronger in the elderly or adults who did not take medications. Conclusions: The results suggest that PM2.5 exert a cardiotoxic effect by increasing the risk of lipid disorders. Improvement of air quality could prevent dyslipidemia by reducing LDL-C and TC levels. Clean air policies should be implemented as public health measures in countries with aging societies, especially developing ones with a high air pollution burden.

Automated summary

Lowering PM2.5 levels was associated with decreases in LDL-C and TC, but not HDL-C or TG. PM2.5 was identified as a risk factor for dyslipidemia, with a stronger effect in the elderly or adults not taking medications. The study suggests that improving air quality can help prevent lipid disorders.