Reactive nitrogen-driven atmospheric multiphase buffering induces unintended concomitant pollution

Atmospheric multiphase buffering capacity is a crucial physicochemical property of aerosol that significantly influences the Earth's radiative budget, climate, air quality, and public health. However, its implications for air pollution remain largely unexplored. Here, we present four years of continuous observation and laboratory experiments as evidence that reactive nitrogen (Nr)-driven atmospheric multiphase buffering can induce unintended Concomitant Pollution. Specifically, gaseous pollutants undergo phase partitioning into aerosol aqueous phases during the process of pH change under buffering constraints, subsequently transforming into concomitant particulate pollution. Furthermore, from a global perspective, we reveal that NH₄⁺/NH₃-induced Concomitant Pollution exhibits greater intensity in South Asia during winter, while in summer, it intensifies in North America, Europe, and East Asia. And anthropogenic emissions, particularly buffering agents like NH₃, exert a greater impact on Concomitant Pollution across continents than meteorological factors. Thus, the relentless rise in global NH₃ emissions has positioned Concomitant Pollution as an urgent challenge.