The impact of levels of particulate matter with an aerodynamic diameter smaller than 2.5 μm on the nasal microbiota in chronic rhinosinusitis and healthy individuals

Air pollution, which has been linked to many human diseases, has been associated with changes in the sinonasal and respiratory microbiome in both healthy and diseased states. Ambient particulate matter (PM) is essentially atmospheric aerosols with adverse health effects depending on their size, and are categorized on the basis of aerodynamic diameter—that is, as particles smaller than 10 μm (PM10), 2.5 μm (PM2.5), and 0.1 μm (ultrafine particles). PM2.5 tends to deposit throughout the respiratory tract and is often composed of combustion particles, organic compounds, and metals less than 2.5 μm.