Current Residents

Second Year Residents

John Bossalini, DO (Chief Resident) is from Albany, New York, and received his bachelor's degree in biology from the University at Albany. He attended medical school at the Lake Erie College of Osteopathic Medicine in Erie, Pennsylvania. He completed a Transitional Year Internship at Brooke Army Medical Center in Fort Sam Houston, Texas. After the internship, he spent four years serving as a Flight Surgeon in the U.S. Air Force at Beale Air Force Base in Beale, California. After separating from the military, he worked as the medical director for an occupational medicine clinic in Newport News, Virginia, for 10 months while applying to residency programs in occupational medicine. He is currently pursuing his Master of Public Health at UC Berkeley as part of his first year in the UCSF Occupational and Environmental Medicine Residency program. He has an interest in aerospace medicine and private practice. 

 

First Year Residents

Rosemarie Dizon DO, is from Great Mills, Maryland, and received her undergraduate degree in Public Health from Rutgers University - New Brunswick in New Jersey. She attended medical school at Campbell University in Buies Creek, North Carolina. She completed her Family Medicine Internship at Naval Hospital Camp Pendleton in 2018 before completing Naval Aeromedical Officer Training in Pensacola, Florida. She served as a Flight Surgeon at Marine Corps Air Station Cherry Point in North Carolina from 2019 to 2021 before returning to complete her Family Residency at Naval Hospital Camp Pendleton in California. Since graduating from Family Medicine residency, Dr. Dizon served a second tour as a Flight Surgeon at Naval Air Station Whidbey Island and deployed with Patrol Squadron 47 before starting OEM residency at UCSF in July 2025. She is a fan of Bay Area sports teams including Bay FC, the 49ers, and the Giants. Her areas of interests include reproductive consequences of occupational hazards in aviation on female veterans as well as noise pollution and it's effects on developing children. 

 

Sophie Jin, MD is from from Baltimore, Maryland and earned an undergraduate degree in Environmental Science from University of Maryland, College Park and attended medical school at University of Maryland in Baltimore. Prior to medical school, Dr. Jin studied socio-environmental impacts of mosquito-borne diseases and worked in HIV outreach. Dr. Jin completed a residency in Emergency Medicine at York Hospital during the height of the COVID-19 pandemic and returned to work in Baltimore City. Dr. Jin is interested in understanding and mitigating environmental impacts on health among vulnerable populations, especially in the context of climate change.

 

Vibhu Krishna, MD graduated from Columbia University and Vanderbilt University, completed PGY1-2 at New York Presbyterian Hospital Columbia-Cornell before transitioning to the West Coast to study Occupational, Environmental, and Climate Medicine at UCSF. Dr. Krishna has a background in Public Health consulting during the pandemic, and clinical experience in preventive, primary, urgent, and emergent care in low-resource settings. She is an avid reader, writer, runner, artist, and yoga instructor with a strong penchant for baked goods. Dr. Krishna is ultimately seeking a career involving clinical, policy, and public health / field work focused on temperature-related illnesses and marginalized populations. 

 

Hector Rivera Marrero, MD is originally from Humacao, Puerto Rico, and also calls Brownsville, Texas, home. He earned his undergraduate degree in Chemistry from the University of Texas Rio Grande Valley. Before attending medical school, Dr. Rivera gained experience in the oil and gas industry, operations, and later served as an Environmental Health System Coordinator. He went on to receive his medical degree from the University of Texas Rio Grande Valley School of Medicine and completed a preliminary year in general surgery at the University of California, Davis. His professional interests lie at the intersection of clinical and corporate occupational medicine. Outside of work, he enjoys spending time with his family and cooking for them.

 

Incoming Residents

E Makar, MD, completed medical school at the University of Maryland and trained in emergency medicine at Dartmouth-Hitchcock Medical Center, where they saw firsthand the impact of preventable illness and injury. They are interested in how environmental and workplace conditions shape health, with a focus on prevention and universal access to care. Their prior work includes prenatal ultrasound capacity-building in Peru and curriculum development in climate and LGBTQ+ health.

Outside of medicine, you can find them walking their dog, climbing rocks, strumming the ukulele, and cooking meals for family and friends. They are excited to explore the Bay Area by bike and scout out the best dim sum spots.

 

Nnedinma Okpala, MD, MPH, MS, earned her medical degree from Meharry Medical College, where she developed a strong commitment to serving underserved and vulnerable populations. She received her Bachelor of Science in Public Health from the University of Texas at San Antonio and a Master of Public Health from UTHealth Houston, where her training focused on advancing health equity and addressing disparities in care, as well as a Master of Science from Meharry Medical College.

Her research, conducted prior to medical school, examined stroke disparities, telemedicine access, and health outcomes in underserved populations, reflecting a sustained interest in population health and the social determinants of health. Currently completing her internal medicine internship at the University of Louisville, Dr. Okpala has gained broad clinical experience managing a wide range of acute and chronic conditions. She remains engaged in community service through initiatives such as the Houston Food Bank and patient education programs aimed at improving health literacy.

Dr. Okpala’s career interests center on advancing workplace safety through evidence-based interventions, optimizing care for the working population, and facilitating safe return to work within corporate settings, while advocating for policies that promote the health of vulnerable workers and underserved communities.

 

Pengse Po, DO, is a U.S. Navy Flight Surgeon with specialized experience in aerospace and operational medicine, currently serving with the United States Navy in San Diego. A graduate of the Philadelphia College of Osteopathic Medicine, Dr. Po also holds a Bachelor of Science in Neuroscience and Biochemistry from the University of Massachusetts Amherst.

In his role as a Flight Surgeon, he conducts comprehensive medical evaluations for aviation personnel, develops training programs to enhance operational readiness, and leads emergency response efforts during flight operations and military exercises. With experience working in high-demand, resource-constrained environments, he brings a mission-focused approach to advance occupational and environmental health.

 

Akber Sheikh, DO, is a graduate of Western University of Health Sciences College of Osteopathic Medicine of the Pacific. He earned his undergraduate degree from University of California, Berkeley, graduating with honors and a strong academic foundation in neuroscience, molecular biology, and the humanities. He is currently completing an internal medicine internship at Southwest Healthcare Medical Education Consortium. 

Dr. Sheikh is committed to advancing health equity through community outreach, pro bono clinic work, and global health initiatives, including a fellowship focused on rural health and development in South Asia. His academic interests span clinical medicine and public health, with several peer-reviewed publications in dermatology, gastroenterology, public health, and beyond. He is passionate about mentorship and medical education and has served as a Medical Spanish teaching assistant, supporting culturally competent care for diverse patient populations.