Inhalable Fungi and Opportunistic Pathogens During Haze and Haze‐Dust Events From Winter to Springtime in One Typical Inland City of Northern China.

Fungal aerosols, as significant biocomponents of inhalable particulate matter, encompass a variety of allergens and pathogens. However, comprehensive knowledge regarding their composition, sources, and opportunistic pathogens present in severe air pollution remains limited. In this study, PM2.5 samples were collected from January to March 2018 in a northern Chinese city, during the winter heating and spring sandstorm seasons. The fungal community characteristics within three distinct haze and haze‐dust composite pollution were examined. The concentration of fungal aerosols was found to be significantly higher in dust samples. This was evidenced by a strong positive correlation with Ca2+, temperature, and wind speed (p < 0.05). Human and animal pathogens, such as Candida, were more prevalent in haze samples. Conversely, allergens and plant pathogens, like Alternaria, were found in higher concentration in dust samples. The primary ecological function shifted from being saprophytic to becoming human‐animal pathogenic or plant‐animal pathogenic. This shift was observed from non‐pollution, haze, to haze‐dust composite pollution. The dispersion of fungal aerosols was influenced by factors such as dust events and meteorological conditions, including increased temperature and wind speed. In the spring dust episodes, dust‐related pollutants, such as soil Ca2+ and PM10, accounted for 51.39% of the variation in the fungal community. This research explored the dynamics of fungal communities, potential pathogens, and factors influencing fungal communities in regional air pollution. The insights garnered from this research provide a robust foundation for subsequent human health exposure assessments. Plain Language Summary: Fungal aerosols, comprising spores, mycelium, and metabolites, harbor a variety of pathogens, and allergens of medical significance. These aerosols have been observed to increase in concentration during regional severe air pollution, necessitating further exploration of their potential harmful effects. This study aimed to elucidate the concentration, community structure, pathogens, and ecological functions of fungal aerosols during severe air pollution. To achieve this, particulate matter samples were collected in the typical periods of heightened pollution (winter heating and spring sandstorm seasons) in a northern China city. During this period, three severe pollution episodes‐defined as haze, haze‐dust synchronous composite pollution, and haze‐dust asynchronous composite pollution‐were identified. Our findings revealed that fungal concentrations were notably high in dust samples. High wind speed and temperature facilitated the dispersion of fungal spores. Winter haze samples were enriched with highly animal pathogenic fungi, while spring dust samples exhibited an elevated abundance of allergens and plant pathogens. Notably, meteorological conditions exerted a more pronounced impact on the fungal community during haze pollution, whereas dust‐related pollutants were the primary factors affecting the distribution and variation of fungal communities in the spring dust episodes. This research offers foundational data for evaluating human health exposure to fungal aerosols. Key Points: Meteorological conditions and air pollutants modulate fungal communitiesHuman pathogenic fungi were enriched in haze samples (Candida)Allergens and plant pathogens (Alternaria) were abundant in dust samples [ABSTRACT FROM AUTHOR]