Dr. Renyi Zhang’s scientific endeavors have advanced the understanding of four pressing global issues: (i) air pollution, (ii) climate change, (iii) stratospheric ozone layer depletion, and (iv) the COVID-19 pandemic. In the realm of air pollution, his investigations have provided critical insights into the fundamental formation mechanisms and impacts of fine aerosols or particulate matter (PM). His groundbreaking work includes first explaining the mysterious chemistry behind the historic 1952 London Fog and contemporary severe hazes in Asia, a critical contribution to air quality improvement worldwide. His research on aerosols and their radiative forcing has far-reaching implications for climate studies and has improved the assessment of black carbon (BC)'s role in global warming. His research has transformed the understanding of aerosol-cloud interactions, their effects on climate, and the global impacts of regional air pollution, all of which are essential for addressing climate change and accurate predicting weather extremes. In addition, his work has shed light on adverse health effects associated with exposure to ultrafine particles and provided the first pivotal evidence on the airborne transmission of COVID-19, with major implications for protecting the public. His earlier research on stratospheric chemistry has been instrumental in understanding the mechanisms behind the Antarctic ozone hole formation. Dr. Zhang played a leading role in establishing a Center for Atmospheric Chemistry and Environments (CACE) and an interdisciplinary research and education program on the impacts of air pollution on human health, which have led to several funded interdisciplinary projects. Dr. Zhang has mentored an elite cadre of early career scientists, including 23 doctoral dissertations, 11 Master theses, 28 postdocs/research scientists, and 14 exchange graduate students. His graduate students have received employments in academia (e.g., a tenured associate professor at Purdue University, an assistant professor at Stanford University, an assistant professor at University of Connecticut, an endowed Professor at University of New Haven, an associate Lab Director at Florida International University, etc.), government (e.g., research scientists at NASA, NOAA, DOE, etc.), and industry (e.g., environmental scientists at Intel Corporation, Samsung, etc.). Numerous of his graduate students have achieved national/international recognitions. He is an elected Fellow of American Association for the Advancement of Science, American Meteorological Society, and American Geophysical Union. He was honored by a named symposium at the 2016 National Meeting of the American Chemical Society and received the Humboldt Research Award in 2023.