low water content and cold temperatures might select which microorganisms can survive in the atmosphere. From the pool of microbial cells being aerosolized from Earth's surfaces, these adverse conditions might act as a filter in selecting cells already resistant to unfavorable physical conditions. Fungal cells and especially fungal spores might be particularly adapted to survive in the atmosphere due to their innate resistance and might behave differently than bacterial cells. Still, the proportion and nature (i.e., fungi versus bacteria) of microbial cells that are resistant to the harsh atmospheric conditions within airborne microbial communities are unknown. Airborne microbial transport is central to dispersal outcomes and several studies have demonstrated diverse microbial biosignatures are recoverable from the atmosphere. Microbial transport has been shown to occur across inter-continental distances above terrestrial habitats. Variation has been recorded seasonally, with underlying land use, and due to stochastic weather events such as dust storms. There is evidence specific bacterial taxa (e.g., Actinomycetota and some Gammaproteobacteria) are preferentially aerosolized from oceans. Over urban areas As a result of rapid industrialization and urbanization, global megacities have been impacted by extensive and intense particulate matter pollution events, which have potential human health consequences. Severe particulate matter pollution is associated with chronic obstructive pulmonary disease and asthma, as well as risks for early death. While the chemical components of particulate matter pollution and their impacts on human health have been widely studied, the potential impact of pollutant-associated microbes remains unclear. Airborne microbial exposure, including exposure to dust-associated organisms, has been established to both protect against and exacerbate certain diseases. Understanding the temporal dynamics of the taxonomic and functional diversity of microorganisms in urban air, especially during smog events, will improve understanding of the potential microbe-associated health consequences. Recent advances in airborne particle DNA extraction and metagenomic library preparation have enabled low biomass environments to be subject to shotgun sequencing analysis. In 2020, Qin et al. used shotgun sequencing analysis to reveal a great diversity of microbial species and antibiotic resistant genes in Beijing's particulate matter, largely consistent with a recent study. The data suggest that potential pathogen and antibiotic resistance burden increases with increasing pollution levels and that severe smog events promote the exposure. In addition, the particulate matter also contained several bacteria that harbored antibiotic resistant genes flanked by mobile genetic elements, which could be associated with horizontal gene transfer. Many of these bacteria were typical or putative