TAPAS K. DAS, PhD, PE, DEE, is a chemical and environmental engineer working with the Department of Ecology Air Quality Program at Olympia, Washington. He is currently engaged in a state and nationwide study to evaluate air toxic emissions and other pollutants from Kraft and Sulfite pulping processes. Dr. Das holds a BSc in chemical engineering from Jadavpur University, Kolkata (formerly Calcutta), India, and PhD from Bradford University, Bradford, England. Dr. Das was a postdoctoral fellow at London's Imperial College of Science, Technology, and Medicine, Department of Chemical Engineering, and at Princeton University. He has wide practical and theoretical experience and expertise in various areas including air toxics and aerosols, wastewater characterization and treatment, solid waste management, and combustion.