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

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 (PM2.5), 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.