BaltimoreRailroadsLightMarylandBedsNoise, TransportationEquipment SafetyBirdsLongitudinal StudiesIatrogenic DiseaseDistrict of ColumbiaProtective DevicesAccidentsUrban PopulationAfrican AmericansVolunteersUnnecessary ProceduresSubstance Abuse, IntravenousAgingAccidental FallsFibrinogens, AbnormalNoiseAction PotentialsPatient SafetyEquipment DesignSmall BusinessDancingResidence CharacteristicsNeedle-Exchange ProgramsMyosin Light ChainsGene FlowTransfer AgreementTime FactorsCross-Sectional StudiesDrug UsersCatchment Area (Health)Urban Health