Effect of Ambient Fine Particulate Matter Air Pollution and Colder Outdoor Temperatures on High-Density Lipoprotein...

Fine particulate matter (PM_2.5) air pollution and environmental temperatures influence cardiovascular morbidity and mortality. Recent evidence suggests that several air pollutants can promote dyslipidemia; however, the impact of ambient PM_2.5 and temperature on high-density lipoprotein (HDL) function remains unclear. We hypothesized that daily exposures to higher levels of ambient PM_2.5 and colder outdoor temperatures would impair HDL functionality. Lipoproteins, serum cholesterol efflux capacity (CEC), and HDL oxidation markers were measured twice in 50 healthy adults (age 32.1 ± 9.6 years) living in southeast Michigan and associated with ambient and personal-level exposures using mixed models. Although previous 7-day mean outdoor temperature (4.4 ± 9.8°C) and PM_2.5 levels (9.1 ± 1.8 µg/m³) were low, higher ambient PM_2.5 exposures (per 10 µg/m³) were associated with significant increases in the total cholesterol-to-HDL-C ratio (rolling average lag days 1 and 2) as well as reductions in CEC by -1.93% (lag day 5, p = 0.022) and -1.62% (lag day 6, p = 0.032). Colder outdoor temperatures (per 10°C) were also associated with decreases in CEC from -0.62 to -0.63% (rolling average lag days 5 and 7, p = 0.027 and 0.028). Previous 24-hour personal-level PM_2.5 and temperature exposures did not impact outcomes, nor were any exposures associated with changes in HDL-oxidation metrics. In conclusion, we provide the first evidence that ambient PM_2.5 (even at low levels) and outdoor temperatures may influence serum CEC, a critical antiatherosclerotic HDL function.