Professor Daniel A. Vallero is a renowned environmental scientist and engineer with four decades of experience. He has advised U.S. government agencies on critical issues like PBTs, climate change, acid rain, and chemical risks. At Duke University, he led the Engineering Ethics program and taught courses on air pollution, sustainable design, and ethics. Vallero has served on the National Academy of Engineering’s Online Ethics Committee and the National Institute of Engineering Ethics. An expert in emerging technologies, he focuses on societal, ethical, and public health challenges related to nanotechnology and environmental biotechnology. His work also encompasses emergency response and homeland security, making him a leading voice in environmental risk and ethics. Professor Trevor Letcher is an Emeritus Professor at the University of KwaZulu-Natal, South Africa, and living in the United Kingdom. He was previously Professor of Chemistry, and Head of Department, at the University of the Witwatersrand, Rhodes University, and Natal, in South Africa (1969-2004). He has published over 300 papers on areas such as chemical thermodynamic and waste from landfill in peer reviewed journals, and 100 papers in popular science and education journals. Prof. Letcher has edited and/or written 32 major books, of which 22 were published by Elsevier, on topics ranging from future energy, climate change, storing energy, waste, tyre waste and recycling, wind energy, solar energy, managing global warming, plastic waste, renewable energy, and environmental disasters. He has been awarded gold medals by the South African Institute of Chemistry and the South African Association for the Advancement of Science, and the Journal of Chemical Thermodynamics honoured him with a Festschrift in 2018. He is a life member of both the Royal Society of Chemistry (London) and the South African Institute of Chemistry. He is on the editorial board of the Journal of Chemical Thermodynamics, and is a Director of the Board of the International Association of Chemical Thermodynamics since 2002.