The Team

Katie Crist, PhD, MPH

Co-Principal Investigator

Dr. Crist has conducted studies to promote physical activity and understand environmental influences on health and behavior for the past 11 years in UCSD’s Department of Family Medicine and Public Health and has recently been appointed to the Urban Studies and Planning Department. Her research aims to increase physical activity and active transportation by integrating behavioral interventions with infrastructure improvements to enhance the effectiveness of urban investments.  Dr. Crist believes that collaboration between public health researchers and transportation/urban planners is essential to create communities that support active lifestyles, health equity and climate sustainability. 

James F. Sallis, PhD

Co-Principal Investigator

James F. Sallis, Ph.D is Distinguished Professor Emeritus in the Herbert Wertheim School of Public Health and Human Longevity Science at University of California San Diego and Professorial Fellow at Australian Catholic University, Melbourne.  His primary research interests are promoting physical activity and understanding policy and environmental influences on physical activity, nutrition, and obesity.  His research has been funded by the National Institutes of Health, Centers for Disease Control and Prevention, and several philanthropic organizations. He was Director of Active Living Research (2001-2015) that helped establish an interdisciplinary field of research to identify effective environmental and policy strategies to increase physical activity.  He is an author of over 750 scientific publications and one of the world’s most cited authors. He is currently focusing on getting research used to create healthier cities. Dr. Sallis is Past-President of Society of Behavioral Medicine and member of the National Academy of Medicine. 

Tarik Benmarhnia, PhD


Tarik Benmarhnia is an environmental epidemiologist with a joint appointment at the University of California San Diego’s Scripps institution of Oceanography and School of Medicine. He finished his PhD in epidemiology jointly from the University of Montreal and Paris Sud and a post-doctoral position at McGill University with the Institute for Health and Social Policy. His work is combining epidemiological methods with environmental and econometric models with a specific focus on health policies and environmental justice.

Lawrence Frank, PhD


Dr. Frank specializes in the interaction between land use, travel behavior, air quality and health; and in the energy use and climate change impacts of urban form policies. He is a “walkability pioneer” and was among the very first to quantify connections between built environment, active transportation, and health. He began using the term “walkability” in the early 90’s and his work led to WalkScore and has been cited over 38,000 times. He has been listed in Thompson and Reuter’s top 1% in the social sciences and is the #1 top ranked planning academic in North America according to a recent Google Scholar ranking. Dr. Frank has published over 200 peer reviewed articles and reports and co-authored Heath and Community Design and Urban Sprawl and Public Health nearly 2 decades ago that mapped out the field emerging at the nexus between built and natural environments and health.

Michael Pratt, MD, PhD


Dr. Pratt is a Professor in the Division of Global Health with expertise in physical activity and public health. Before coming to UC San Diego, he was a Visiting Professor in the Hubert Department of Global Health, Rollins School of Public Health, at Emory University and a Medical Officer at the National Center for Chronic Disease Prevention and Health Promotion at CDC, including serving as the Senior Advisor for Global Health and as the first Chief of the Physical Activity and Health Branch.

He founded the CDC World Health Organization Collaborating Center for Physical Activity and Health and the International Physical Activity and Public Health Course. Dr. Pratt has also been an Adjunct Professor at the Schools of Medicine and Government at los Andes University in Bogotá, Colombia and a Visiting Professor at the Federal University of Pelotas in Brazil. He completed a Masters Degree in exercise physiology and Medical Degree at the University of Washington in Seattle, medical residency training at the Mayo Clinic in Minnesota, earned a Masters Degree in Public Health at the University of Minnesota, and is a graduate of the EIS epidemiology fellowship and preventive medicine residency at CDC. He is board certified in General Preventive Medicine and Public Health and is a Fellow in the American College of Preventive Medicine and the American College of Sports Medicine. Dr. Pratt’s research interests include increasing global research capacity for physical activity and chronic disease prevention, physical activity intervention strategies, and evidence-based public health

Elizabeth Zunshine, MS, RDN

Project Manager

Elizabeth Zunshine is a Registered Dietitian with over 17 years of experience in design, delivery, and dissemination of multiple research studies. She grew up in New Mexico and ventured out to San Diego to gain a Master’s Degree in Nutritional Science from San Diego State University. She completed a public-health based internship with the Tri-Country Health Department in Denver, Colorado and became a Registered Dietitian Nutritionist. She also taught college-level courses in Nutrition at Grossmont College and and is currently involved in several nutrition and public health-based studies at UCSD. Whether as a Dietitian or Project Manager, Liz has a true passion for helping others improve their health and wellbeing. In her free time, she enjoys being active outdoors, traveling, and enjoying various foodie adventures with her husband. 

Dana Song, MPH

Research Associate

Dana Song (she/they) received her MPH from the Herbert Wertheim School of Public Health and Human Longevity Science in 2021. She has over 5 years of experience assisting various studies, such as the Peer Empowerment Program 4 Physical Activity (PEP4PA) study and the SANDAG Shared Streets 2.0 Pilot project. One of her main interests are improving accessibility and safety in active transportation for all (often pondered while biking to work herself). She enjoys all things bikes, hikes, the outdoors, and art.