Meet the Team

Christopher Hartsfield became CS' Programs Director in January 2020, overseeing daily direct service for nearly 400 children and youth as well as single-day programming for thousands of children and community members. From 2015 - 2018, Christopher led CS' Outdoor Play programming for 7-24-year-olds, including teaching after school children and youth interns how to co-lead cycling adventures, fitness circuits and testing, JungleGym (CS' obstacle race and active-living fair), and over 35 single-day play events per year. In 2019, Christopher transitioned to Programs Manager, leading program service delivery for CS’ Outdoor Leadership Academy - Summer Youth Employment Program and expanded its OLA-Kids programming from after school to summer camp. Christopher earned a B.S in Health & Physical Education from Elizabeth City State University, and has a Wilderness First Aid Certification from SOLO, a Middle Manager Certificate from the American Camp Association, and Outdoor Leadership Training from the Appalachian Mountain Club's Youth Opportunities Program. In 2019, Christopher completed the Developing Leaders Program for Nonprofit Professionals at Columbia Business School and the Family Development Credential for Leaders with the NYC Department of Youth. Prior to joining CS, Christopher was a fitness coach and floor trainer at the YMCA Armory in Park Slope instructing 4-18-year-olds in various sports classes and the youth basketball league. He is a licensed security and fire brigade officer, and demonstrates a serious commitment to safety.

Executive Director Mac Levine, MPH, founded CS in 2008 with 16 East Harlem children, and has since grown the organization to serve over 19,000 children, youth, and families. She earned a Masters of Public Health from Columbia University's Mailman School of Public Health in the Built Environment Track, where she won the John and Kathleen Gorman Public Health Humanitarian Award. Mac also graduated cum laude from Northeastern University with a bachelor's degree in music industry and a minor in sociology. Mac is a Certified Nonprofit Accounting Professional and a graduate of the National Outdoor Leadership School. She holds a Camp Director Certificate of Added Qualification from the American Camp Association and Wilderness First Aid. She was recognized in CUNY's 2017 Class of 40 Under 40: The Rising Stars in New York City Food Policy. She has guest lectured at Columbia University, New York University, Icahn School of Medicine at Mount Sinai, The New School, and Northeastern University, and presented at the Just Food, American Community Gardening Association, and Hindsight Conferences. She is a co-author of "Closing Health Disparities Through A Multi-Level Approach," published in the International Journal of Child and Human Development as well as in the book Environmental Health Disparities: Costs & Benefits of Breaking the Cycle in 2016. She has been honored by the 25th Precinct with a Women of Excellence Award. Mac was the first solo female to stand-up paddle (SUP) the Hudson River Water Trail without assistance from Albany to Manhattan in June 2014, and the first person to SUP all five boroughs on the NYC Water Trail in 2015. She has completed the NYC Skate Marathon twice.

Nafis Khan became the Administrative Coordinator in 2025 after leading recruitment, supervision, and organization of Public Health AmeriCorps Members as CS' PlacemakingCorps Coordinator in 2024. He first joined the Concrete Safaris team as a Health Promotion Intern in 2022 through OLA-CUNY after his sophomore year of college in 2022. In November of 2022, Nafis transitioned to becoming the Health Promotion Lead. Nafis earned his B.S in Health Psychology from CUNY Hunter College in 2023 and will begin graduate school to earn his Doctorate of Physical Therapy next year. Outside of work, he enjoys playing sports outdoors and coaching youth AAU basketball.

Savannah Nicholas has served as the Education Coordinator for Concrete Safaris' Outdoor Leadership Academy - SYEP since 2023. Her journey with Concrete Safaris began in 2019, when she joined as an Outdoor Play Intern through the same program. Over the years, she has continued to grow within the organization, taking on impactful roles such as Social and Emotional Learning Ambassador, where she thrives as a dynamic and empathetic leader.

Savannah has graduated from the Illustrious Virginia State University with a Bachelor's of Science in Mathematics. She plans to further her education and pursue her masters degree in data science. Beyond her academic and professional commitments, Savannah enjoys painting and staying active through regular workouts.

Joycelyn Umar became the Project Developer in 2025. She served as a Public Health AmeriCorps Member at Concrete Safaris' PlacemakingCorps in the 2024/25 term. She graduated from York College-CUNY with a Bachelor's in Health Science and earned her Master's in Public Health from CUNY Graduate School of Public Health and Health Policy in the Health Policy and Management Concentration. Her hobbies are reading novels, cooking at home and planting flowers.