Opportunities, challenges, and policy implications of the aerobiome paradigm shift.

Historically, bioaerosol research has focused on identifying and mitigating the harmful effects of airborne pathogens and particles. These bioaerosols-including bacteria, viruses, fungal spores, and non-biological particles, such as particulate matter up to 2.5 µm (PM2.5)-pose substantial risks to human and ecosystem health. They can contribute to diseases and adverse outcomes in humans, animals, plants, and their associated microbial communities. Researchers have concentrated on understanding transmission mechanisms, detecting and quantifying these agents, and developing control strategies. However, a recent paradigm shift in aerobiome thinking highlights the importance of beneficial bioaerosols in maintaining ecosystem and human health. Beneficial bioaerosols, such as salutogenic (health-promoting) microbiota, phytoncides (plant-derived organic compounds), pheromones, and potentially "aeronutrients" contribute to human health modulation and important ecosystem processes. This dual nature of bioaerosols necessitates a holistic approach to promote beneficial components while mitigating harmful ones. Here, we introduce a recently established initiative called the Aerobiome Innovation and Research Hub (AIR Hub), which aims to advance this interdisciplinary research. We call for action to further understand and leverage the beneficial biological components of air for both human and ecosystem health and present the results of an AIR Hub workshop "reverse brainstorming" session to identify novel opportunities and challenges. These include key barriers to advancing aerobiome science, such as poor communication, methodological complexity, and fragmented regulation. Solutions focused on clearer definitions, improved research methods, targeted communication, and stronger policy engagement. Finally, we present the key policy implications of advancing this aerobiome paradigm shift.