From urban centers to remote mountain ranges, the quality of the air we breathe is profoundly shaped by intricate physical and chemical mechanisms. Atmospheric processes & air quality explores the dynamic interactions among pollutants, meteorological conditions, and atmospheric chemistry that govern the distribution and transformation of airborne substances. Ground-level ozone formation, aerosol-cloud interactions, and long-range transport of particulate matter are among the key phenomena under investigation. Researchers are increasingly leveraging machine learning and high-resolution atmospheric modeling to improve forecasting accuracy and pollution source attribution. Additionally, the intersection of human health and atmospheric science is receiving heightened attention, particularly in the context of respiratory illnesses and climate-linked air quality degradation. By unpacking the fine-scale processes that influence air composition, the study of Atmospheric Processes & Air Quality supports regulatory development, public health planning, and urban sustainability initiatives on both local and global scales.