The Human Microbiome in Airborne Particulate Matter-Associated Aging-Related Chronic Diseases: An Evidence-Stratified...

Airborne particulate matter (PM) exposure is increasingly recognized for its profound impact on human health. Emerging evidence highlights the human microbiome as a plausible intermediary between environmental exposures and host physiological responses. While current research largely focuses on PM's direct toxicological effects, the role of microbiome disruption in mediating aging-related chronic diseases remains underexplored. This review integrates epidemiological data, animal models, and multiomics approaches to examine the impact of PM exposure on microbial communities across the respiratory, gut, and skin microbiomes, with a particular focus on the gut microbiome's role in aging phenotypes. We propose an evidence-stratified PM Exposure-Microbiome-Aging framework, in which the microbiome is considered a plausible exposure-sensitive interface linking environmental exposure to health outcomes, with the gut microbiota representing the most mechanistically developed interface in the current literature. By synthesizing current evidence on microbiome-linked pathways relevant to PM-associated chronic disease risk, this review provides a structured framework to guide future mechanistic and translational research.