Personal monitoring of exposure to PM_2.5 and PM_coarse: A panel study of lung function and oxidative stress biomarkers in elderly Hong Kong residents

While fine particulate matter (PM_2.5) has been extensively studied for its cardiorespiratory risks, the toxicological significance of coarse particulate matter (PM_coarse) remains poorly characterized due to methodological challenges in exposure assessment. This panel study employed personal exposure monitoring to unravel the distinct respiratory and oxidative stress effects of PM_2.5 versus PM_coarse and their chemical constituents in vulnerable elderly. Intensive 6-day monitoring of 48 healthy elders in Hong Kong was conducted during each campaign, combining real-time personal PM sampling (analyzed for organic/elemental carbon, PAHs, and ionic species) with daily lung function tests (FEV₁, FVC, PEF) and urinary biomarkers (8-OHdG, MDA). The mixed-effects model was controlled for microenvironmental factors (temperature/humidity) and individual characteristics (BMI, age, gender). Personal exposure to sulfate ions (SO₄²⁻) in PM_2.5 showed a significant inverse relationship with the FEV₁/FVC ratio, indicating impaired lung function. Notably, increased personal exposure to PM_coarse was associated with elevated levels of the oxidative stress biomarker 8-OHdG. Furthermore, the findings reveal a pronounced impact of personal PAHs exposure on MDA levels, with the effects being more substantial for PM_coarse (15.71 %) relative to PM_2.5 (3.53 %). These findings provide somewhat evidence for the health impacts of PM_coarse, likely driven by its chemical composition and size-dependent effects. Highlighting the overlooked role of PM_coarse in adverse health outcomes, this study underscores the necessity of including PM_coarse and its components in health impact assessments and regulatory standards.