Association of airborne particulate matter with pollen, fungal spores, and allergic symptoms in an arid urbanized area

Abstract: Studies focused on the seasonal distribution of pollen and spores in semiarid cities are scarce. At these sites, climate change potentiates the emission and transport of fine (PM₁₀) to ultrafine particles (PM_2.5), easily attached to pollen surfaces, causing allergen’s release. This study examines the potential correlation of seasonal variations of pollen, fungal spores, PM₁₀, and meteorological parameters with allergic reactions of 150 people living in a Sonoran desert city. We collected PM₁₀, airborne pollen, and spores during a year. We also studied topsoil and road dust samples as potential PM-emission sources. We obtained dust-mineralogy, chemistry, and particle size attached to pollen by X-ray diffraction and scanning electron microscope. Results show that seasonal high PM-loading in the urban atmosphere coincides with aeroallergens promoting micro- to nanoparticles’ attachment to pollen’s surface. A collapsed membrane was observed in several samples after individual grains show the following maximum wall coverage: Poaceae 28%, Asteraceae 40%, Chenopodiaceae-Amaranthacea 29%, Fabaceae 18%. Most of the particles covering pollen’s surface have a geogenic origin mixed with metals linked to traffic (bromide, chlorine, and antimony). Mineralogical, granulometric analysis, and main wind-direction show that two local soil-types are the main contributors to PM. A high frequency of positive sensitization to pollen with high particle loading was detected. These results suggest that climate-driven dust emissions may alter pollen and spore surfaces’ physicochemical characteristics with the further consequences in their allergenic potential. Graphic abstract: [Figure not available: see fulltext.]