Dr. Shell has 18 years of experience in the field of public health, serving at both the state and local level. He is currently the Director of the Cancer and Chronic Disease Bureau in the Maryland Department of Health and Mental Hygiene. As the Director of the Cancer and Chronic Disease Bureau, Dr. Shell is responsible for the oversight of the Center for Tobacco Prevention and Control, the Center for Chronic Disease Prevention and Control, the Center for Cancer Surveillance and Control, and the Office of Oral Health.

Dr. Shell believes that critical healthcare choices, some in, and some out of the control of individuals and populations, are impacted by their relationships, education, life experiences, housing, employment, nutrition, finances, emotions, substance use, spirituality, and their ability to trust. He believes that each of these social determinants must be taken into consideration when developing, delivering, and evaluating health and social services.