Ambient PMs pollution, blood pressure, potential mediation by short-chain fatty acids: A prospective panel study of young adults in China

Background: The concurrent effects of particulate matter (PM) on both blood pressure (BP) and short-chain fatty acids (SCFAs) are insufficiently explored, with limited research on the potential mediating roles of SCFAs.

Methods: In this prospective panel study with 4 follow-ups, we recruited 40 college students in Hefei, China, to assess the impacts of short-term exposure to PM (aerodynamic diameter ≤10 μm (PM₁₀), ≤2.5 μm (PM_2.5), and ≤1 μm (PM₁)) on BP and SCFAs, along with potential mechanisms. Real-time PM data, urinary SCFAs levels, and BP indicators were systematically collected. Linear mixed-effects models assessed the relationships between PM, SCFAs, and BP. Mediation analyses explored SCFAs' mediating role in the PM-BP association.

Results: PM exposure was positively linked to BP and negatively associated with SCFAs. For a 10 μg/m³ rise in PM₁₀ at lag 0-72 h, there were notable reductions of 0.0019 % (95 %CI: -0.0028, -0.0010) in Acetic acid, 0.0262 % (-0.0369, -0.0155) in Propionic acid, and 0.0702 % (-0.1025, -0.0378) in Butyric acid. Systolic BP, diastolic BP, and mean arterial pressure (MAP) increased by 2.60 mmHg (0.96, 4.25), 2.24 mmHg (1.18, 3.31), and 2.36 mmHg (1.20, 3.53), respectively, per 10-μg/m³ rise in PM₁ at lag 0-24 h. Decreased SCFAs levels explained significant portions (24.69-31.80 %) of the elevated MAP due to PM₁₀. Stronger associations were found in females and individuals with abnormal BMI.

Conclusions: Our study shows that PM exposure decreases urinary SCFAs levels, which partially mediate the impact of PM on elevated BP. These findings enhance our comprehension of the pathways linking PM exposure to BP changes.