Reactive trace gases comprise a fraction of the Earth’s atmosphere, yet their chemistry strongly influences many atmospheric processes, Earth’s climate, ecosystem functions, and our health. Pollutants like ozone and nitrogen oxides are typically associated with urban anthropogenic pollution; however, regulatory controls have led to dramatic reductions in their concentrations. As a result, we are entering an era in which the biosphere (natural and managed) plays the dominant role in regulating air pollution related atmospheric chemistry. Atmosphere-biosphere interaction mechanisms are complex, variable, and among the most uncertain processes driving tropospheric trace gas composition and chemistry. We are an atmospheric chemistry research group in the Department of Environmental Sciences at the University of Virginia focusing on (1) chemistry-climate feedbacks, (2) mechanisms of atmosphere-biosphere exchange, articulating specific organismal processes that alter atmospheric chemistry and composition, (3) long-term trends in chemical oxidation, capitalizing on extemporary atmospheric experiments and the wealth of multi-year composition data, and (4) air pollution environmental justice. We combine aircraft, ground-based field, and laboratory measurements to do this work.