Background: Short-term associations between size-fractionated particulate air pollution and circulating biomarkers are not well established, especially in developing countries with high levels of particulate matter (PM).
Methods: We designed a panel study involving 34 healthy young adults to evaluate acute effects of size-fractionated PM on 13 circulating biomarkers of inflammation, coagulation, and vasoconstriction. We measured real-time, size-fractionated number concentrations of PM (aerodynamic diameters from 0.25 to 10 μm, mass concentrations of PM < 10 μm) over four follow-up measurements. The short-term associations between size-fractionated PM and biomarkers were assessed using linear mixed effect models.
Results: We found positive associations between short-term exposure to PM and 10 biomarkers. PM with smaller size had stronger associations. The size fractions with the strongest associations were 0.25-0.40 μm for number concentrations and <1 μm for mass concentrations. For example, an interquartile range increase in 24-hour-average number concentrations of PM0.25-0.40 was associated with a 7%-32% increase in biomarkers of inflammation, 34%-68% of blood coagulation, and 45% of vasoconstriction. Similar estimates were found for mass concentrations of PM1. Furthermore, our results demonstrated an apparent acute effect on circulating biomarkers, even 2 hours after exposure. The effects were strongest within the first 12-24 hours, and effects on inflammation occurred more quickly than on coagulation and vasoconstriction.
Conclusions: Our results provided potentially vital insights into the size and temporal characteristics of PM that could modify subclinical cardiovascular effects. These findings may have implications on disease prevention and environmental regulation in China.