From apprentice to John George, Chappell Hayes, and Wilson Riles, Jr., David was among the first African Americans to distinguish themselves as environmentalists in the San Francisco Bay Area. David has come into his own working with such organizations as Ecology Now, the Institute for Urban Habitat, Communities for a Better Environment, the Sierra Club, and Inner City Outings.  By combining his urban experience with an academic background in city and regional planning, and community development, he has successfully worked on environmental justice issues in Oakland, Berkeley, Richmond, San Francisco and Santa Rosa, California, St. Louis, Missouri, Sao Paolo and Rio de Janeiro, Brasil, Asuncion, Paraguay and Hong Kong. He has worked on projects with regional organizations such as the Bay Area Air Quality Management Board, the Association of Bay Area Governments, and the Airport and Port of Oakland.