Bioaerosol research: Yesterday, today and tomorrow

Bioaerosols have important impacts on many scientific fields, including atmospheric environment, ecology, climate change, food safety, anti-bioterrorism, infectious diseases, public health and environmental health. This review was carried out based on the scientific outcomes from the 600th Xiangshan Science Conference held in Beijing, for whcih 47 scientists including those overseas were invited to discuss the bioaerosol research progress. Over the past 10 years, great strides have been made in the bioaerosol field, such as the expansion of research directions, research broadness and also scientists. For example, atmospheric chemistry researchers have also started to carry out studies about bioaerosol impacts on the atmospheric environment, including those on the cloud droplets, the climate and bioaerosol dynamics during haze events. In addition, new methods and instruments for bioaerosol studies are increasingly being developed in bioaerosol monitoring and capture systems, various biosensors, microfluidics, high-throughput sequencing, and they have helped the scientific community obtain a better understanding of microbes in the air. In terms of health effects, human and indoor bioaerosol emissions have become one of the hot research areas. In addition, bioaerosols were also shown to directly affect the oxidation potential of atmospheric particles and thus on the human health, however, the relevant mechanisms remain to be very limited and could be far more complex than what we have known so far. On the other hand, respiratory infections/outbreaks, caused largely by the spread of bioaerosols, continue to be a major killer for humans, especially for younger children. Currently, although a significant progress has been made in high-throughput screening of respiratory pathogens, the airborne disease transmission mechanisms are still not well understood, including the influences on the pathogen viability and effective transmission distance. The risk of military conflicts in certain regions is increasing, which could potentially lead to possible use of biological weapons via bioaerosol for mass human destruction. In addition, the airborne transmission of antibiotic resistant genes has also received wide attention as an emerging biological pollutant. By integrating sampling, microfluidics, biosensors and electronics, the scientists have taken an important step towards real-time online bioaerosol screening and biological hazard early warning. As a special type of bioaerosol, biomarkers in exhaled breath are also increasingly being studied for early disease diagnosis and screening. At the same time, surgical and nosocomial infections caused by the spread of bioaerosols in the hospital settings are also receiving wide attention. The scientific researchers have also made significant advances in the controlling airborne biological agents, e.g., microwave irradiation, cold plasma and nanomaterial filtration. This review intends to broadly review current state-of-the-art advances in bioaerosol studies, to summarize and discuss the existing problems, correspondingly providing references for the future studies. Despite of great progress made in many aspects of bioaerosols, our understanding of its significance and relevant impacts on our surroundings and health is still quite limited. In the years to come, bioaerosol research is expected to turn a new chapter if multidisciplinary collaboration can be further strengthened.