Temporal Dynamics of Bacterial Aerosols in Haze and Sandstorm Events: Implications for Atmospheric Processes and Public Health

The health impacts of air pollution are deeply intertwined with the composition of pollutants, with bioaerosols—microbial particles suspended in the air—playing a critical role. Despite their importance, the behavior of bioaerosols during pollution episodes remainslargely elusive. In this study, we investigated the dynamics of bacterial aerosols over a one-week period. During the sampling period, haze and sandstorm events occurred sequentially, with a transition period in between. Haze air pollution, characterized by high levels of PM_2.5, is a typical form of anthropogenic pollution, whereas sandstorm dust events, characterized by high levels of PM₁₀, are typical natural pollutions. We applied 16S rDNA and 16S rRNA sequencing techniques to explore the total bacterial community and the active bacteria, respectively. Our results revealed distinct bacterial aerosol profiles during haze and sandstorm conditions. Notably, the greatest bacterial diversity was found in sandstorm samples, with the least diversity observed during haze periods. The bacterial aerosols during haze showed the most significant differences compared to those during the transition period, particularly when contrasted with sandstorm samples. The active bacterial profiles, as determined by 16S rRNA sequencing, were found to be dissimilar from the total bacterial communities present during sandstorms. The ecological drivers shaping bacterial community structures also exhibited distinct patterns. Our data suggest that selective forces influence the composition of active bacterial communities in sandstorm samples, as well as the total bacterial population during haze events. A common feature during both haze and sandstorm episodes was the extended residence time of bacteria in the atmosphere, implying that prolonged exposure could alter the structure of airborne bacterial communities. Additionally, our results highlight the increased presence of several pathogens or opportunistic pathogens in the active bacterial communities of sandstorm samples and the total bacteria during haze, indicating a increased health risk for humans, animals, and plants.