Dr. Brown obtained his internal medicine and pulmonary training at Johns Hopkins University and UCSF. Beginning in 1981, he served as Assistant or Acting (2002-2004) Chief of Pulmonary, Critical, and Sleep Medicine at the San Francisco VA Medical Center. He was chief of outpatient pulmonary clinics and the pulmonary function laboratory at the VA until 2017 and founded and directed the Sleep Medicine Program until Dr. Sarmiento’s arrival here the same year. He also founded and continues to direct the Lung Cancer Screening Program at the VA. He has had a strong interest in internal medicine resident education and directed a rotation for UCSF medical residents in the chest clinic at the VA from 1995 to 2017. He was VA site director for the UCSF pulmonary fellowship program from 2004 until 2018. He continues to serve as an attending physician on the inpatient pulmonary rotation, chest clinic, and ICU at the VA. He also oversees a weekly Wednesday noon-hour pulmonary clinical conference at the VA and is a member of Dr. Meshell Johnson's Health Equity Council. He has chaired the UCSF Department of Medicine’s Clinical X Search Committee since 2013.

From 1979 to 2006, Dr. Brown directed a research program focused on regulation of contractile responses, remodeling, and growth of airway smooth muscle cells. More recently, his research has related to implementation of lung cancer screening using low-dose chest CT scans in the VA. He has served as Chair, VA Subcommittee, of American Thoracic Society’s Research Advocacy Committee since 2009. In this role, he advocates for the the VA’s Research and Development Program particularly in areas of improving the research laboratory infrastructure, strengthening the VA Research Career Development Award Program, increasing the visibility of VA-focused sessions at ATS International Conferences, and finding ways to expand access to and effectiveness of lung cancer screening using low-dose chest CT scans in Veterans. He now serves as Chair of ATS’s Research Advocacy Committee. This committee works collaboratively with the National Institutes of Health, the Veterans Administration, the Centers for Disease Control and Prevention, and the Agency for Healthcare Research and Quality to advance research in pulmonary, critical care, and sleep medicine. He is editor of the ATS's Research News Quarterly.