Abstract
Summary The outbreak of the COVID‐19 epidemic is a reminder that aerosols have important health effects as a potential route for disease transmission. Biological components in aerosols (especially PM 2.5 ) may pose potential threats to humans as pathogens and allergens. Research on PM 2.5 and biological components currently focuses mainly on polluted conditions, with less emphasis on clean environments. Sampling has also been primarily based on a single point with a lack of data at different positions. In this study, a modified fluorescein diacetate hydrolysis method was used to measure microbial activity in PM 2.5 at different altitudes over a year in Beijing, China. A high‐throughput sequencing method was used to study the microbial community. Results showed that microbial activity 1.5 m (0.0465 ng m −3 ) above the ground was higher than 31.5 m (0.0348 ng m −3 ). There was higher microbial activity at both heights during spring. Furthermore, a positive correlation was observed between microbial activity and relative abundance of dominant species. Microbial activity increased during autumn and winter increased alongside the pollution level, but in spring higher levels of microbial activity were observed in excellent or good weather conditions. The results from this study are valuable for further research regarding the biological components of atmospheric PM, the prevention of biological pollution, and establishing a comprehensive air quality evaluation system.