The association between ambient air pollution and blood lipids: A longitudinal study in Shijiazhuang, China

Few studies have explored the associations between ambient air pollution and blood lipid levels. This study aimed to fill this knowledge gap based on a routine health examination cohort in Shijiazhuang, China. We included 7063 participants who took the routine health examination for 2–3 times at Hebei General Hospital from January 2016 to December 2018. Individual serum levels of cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) were measured. Their three-month average exposure to air pollution prior to the routine health examinations was estimated using inverse distance weighted method. We used linear mixed-effects regression models to examine the associations between air pollution and levels of blood lipids while controlling for age, gender, body mass index (BMI), smoking, alcohol drinking, temperature, humidity, with a random effect for each individual. Particles with diameters ≤2.5 μm and ≤10 μm (PM2.5 and PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2) and ozone (O3) were all positively associated with TC, TG, and LDL-C and negatively associated with HDL-C, in single pollutant models. Each 10 μg/m3 increment of 3-month average PM2.5 was associated with 0.65% [95% confidence interval (CI): 0.03%–1.28%], 0.56% (95%CI: 0.33%–0.79%) and 0.63% (95%CI: 0.35%–0.91%) increment in TG, TC, and LDL-C, and 0.91% (95%CI: 0.68%–1.13%) decrease in HDL-C. In two-pollutant models, the effects of gaseous pollutants on blood lipids were weakened, while those of PMs were strengthened. Stronger associations were presented in the elderly (≥60 years) and overweight/obese (BMI ≥ 24) participants. Ambient air pollution had significantly adverse effects on blood lipid levels, especially in overweight/obese and elderly individuals. Significant associations between increased air pollution and worse blood lipid levels were found, especially in overweight/obese and elderly individuals.