John Spengler, Akira Yamaguchi Professor of Environmental Health and Human Habitation, and Co-Director of the JPB Environmental Health Fellowship Program at the Harvard T.H. Chan School of Public Health, has over 40 years’ experience in environmental health and exposure science, characterizing the exposure to and effects of contaminants in outdoor and indoor environments. Through studies of homes, office buildings, schools, and transit systems, Spengler’s research has investigated design, materials, maintenance, and behaviors that mitigate exposures to harmful contaminants. During the SARS CoV-2 pandemic, his team examined transmission and mitigation of airborne viruses in schools, airplanes, airports, and buses. Several recent studies have looked at health and the built environment and the wellbeing benefits of exposure to Nature, including using Virtual Reality to explore physiologic and cognitive effects of exposures to nature in indoor and outdoor settings. For the past decade, Spengler’s teaching and research have increasingly focused on issues related to climate change and sustainability. Motivated by the urgency conveyed by the UN Sustainable Development Goals (SDGs), his team has formed collaborations with professional organizations, NGOs, and companies to affect evidence-based decisions more rapidly in other sectors of society.