Exploring the disparity of inhalable bacterial communities and antibiotic resistance genes between hazy days and non-hazy days in a cold megacity in Northeast China.

• The gram-negative bacteria abundance on hazy days were higher than on non-hazy days. • Haze pollution increased bacterial metabolism, cell damage and death. • Hazy days held more pathogenic compositions and higher abundance than non-hazy days. • More ARG sub-types and abundance were detected on hazy days than on non-hazy days. The physicochemical properties of inhalable particles during hazy days have been extensively studied, but their biological health threats have not been well-explored. This study aimed to explore the impacts of haze pollution on airborne bacteria and antibiotic-resistance genes (ARGs) by conducting a comparative study of the bacterial community structure and functions, pathogenic compositions, and ARGs between hazy days and non-hazy days in a cold megacity in Northeast China. The results suggested that bacterial communities were shaped by local weather and customs. In this study, cold-resistant and Chinese sauerkraut-related bacterial compositions were identified as predominant genera. In the comparative analysis, higher proportions of gram-negative bacteria and pathogens were detected on hazy days than on non-hazy days. Pollutants on hazy days provided more nutrients (sulfate, nitrate and ammonium) for bacterial metabolism but also caused more bacterial cell damage and death than on non-hazy days. This study also detected increases in the sub-types and average absolute abundance of airborne resistance genes on hazy days compared to non-hazy days. The results of this study revealed that particle pollution promotes the dissemination and exchange of pathogenic bacteria and ARGs among large urban populations, which leads to a higher potential for human inhalation exposure. [ABSTRACT FROM AUTHOR]