Distinct responses of airborne abundant and rare microbial communities to atmospheric changes associated with Chinese New Year

Airborne microorganisms, including pathogens, would change with surrounding environments and become issues of global concern due to their threats to human health. Microbial communities typically contain a few abundant but many rare species. However, how the airborne abundant and rare microbial communities respond to environmental changes is still unclear, especially at hour scale. Here, we used a sequencing approach based on bacterial 16S rRNA genes and fungal ITS2 regions to investigate the high time‐resolved dynamics of airborne bacteria and fungi and to explore the responses of abundant and rare microbes to the atmospheric changes. Our results showed that air pollutants and microbial communities were significantly affected by human activities related to the Chinese New Year (CNY). Before CNY, significant hour‐scale changes in both abundant and rare subcommunities were observed, while only abundant bacterial subcommunity changed with hour time series during CNY. Air pollutants and meteorological parameters explained 61.5%−74.2% variations of abundant community but only 13.3%−21.6% variations of rare communities. These results suggested that abundant species were more sensitive to environmental changes than rare taxa. Stochastic processes predominated in the assembly of abundant communities, but deterministic processes determined the assembly of rare communities. Potential bacterial pathogens during CNY were the highest, suggesting an increased health risk of airborne microbes during CNY. Overall, our findings highlighted the “holiday effect” of CNY on airborne microbes and expanded the current understanding of the ecological mechanisms and health risks of microbes in a changing atmosphere. The hour‐scale dynamics of bacteria and fungi in the atmosphere were determined. Human activities during Chinese New Year changed the distribution of air pollutants and subsequently affected communities of airborne bacteria and fungi, distinctly. In addition, our results found that abundant species were more sensitive than rare taxa in response to environmental changes associated with Chinese New Year (CNY). The relative abundance of potential bacterial pathogens in the bacterial community was higher during CNY compared with those before and after CNY, which indicated that human activities during CNY increase the threats of airborne microbes to human beings. Highlights Hour‐scale dynamics of airborne bacteria and fungi were determined. Human activities during Chinese N