IF you collect information on individually identified participants from publicly available sources, the project may be exempt, as long as the identifiable information would not cause harm to the individual if it were known. For example, recording observations of everyday public behavior, or interviewing people about non-controversial opinions or preferences.
IF the personal identifying information could harm the participant, then the project would need to be reviewed by the IRB. The IRB might require informed consent to be obtained including a description of the confidentiality procedures to be used. The IRB should be convinced that the subject can understand the procedures for confidential handling of the information as communicated in the consent process.