The April 20, 2010, explosion and collapse of the BP Deepwater Horizon oil platform in the Gulf of Mexico resulted in the release of millions of barrels of oil into Gulf waters. The response to this disaster involved the efforts of tens of thousands of workers in a variety of capacities across Louisiana, Mississippi, Alabama, Florida, Texas, and in the Gulf of Mexico itself. The diverse work included oil and tar ball removal from beaches, oil skimming and booming near shores, burning of surface oil near the source of the oil release, surface application of dispersant by vessels and aircraft, and containment and recovery work on vessels at the release site. The nature of these activities raised concerns about potential occupational exposures to chemical and physical hazards and mental stressors. The Deepwater Horizon oil release was an unprecedented event in the United States in many respects, requiring response work across a vast area of multiple jurisdictions. The type, location, and quantities of oil released; the types and quantities of dispersant used; and climatic and geographical conditions differentiate this release from past oil spills. On May 28, 2010, the National Institute for Occupational Safety and Health (NIOSH) received a request for a health hazard evaluation (HHE) from BP management concerning health effects experienced by responders to the oil release. The request was prompted by the May 26, 2010, hospitalization of seven fishermen who were working in BP's Vessels of Opportunity (VoO) program in the Gulf of Mexico. The fishermen had been hospitalized for symptoms that were initially believed to be related to exposures experienced during their response activities, particularly booming and skimming oil. In response to this request, we began an investigation on June 2, 2010, with an opening meeting held at the BP Operations Center in Houma, Louisiana. In attendance were representatives from NIOSH, BP, the Center for Toxicology and Environmental Health (CTEH), O'Brien's Response Management, the U.S. Coast Guard (USCG), and the Occupational Safety and Health Administration (OSHA). Objectives of this opening meeting were to discuss the initial investigations conducted by CTEH and OSHA into the events surrounding the hospitalization of the fishermen and to plan the NIOSH investigation. These plans included interviews, health symptom surveys, and on-site industrial hygiene assessments of response work activities similar to those performed by the fishermen. As the plans were developing, BP requested that we expand the scope of the HHE to include all major offshore response activities. In addition to oil booming and skimming conducted by workers on VoO vessels, these activities included aerial and vessel-based dispersant releases, in-situ surface oil burning, containment and recovery work at the oil source, and other related offshore oil removal activities. In the weeks that followed, teams of NIOSH industrial hygienists, medical officers, and other occupational health specialists conducted on-site investigations at locations throughout the Gulf region to collect quantitative and qualitative data on potential worker exposures, health symptoms, work practices and procedures, and work organization. On June 22, 2010, NIOSH received a request from BP for a second HHE to investigate potential hazards associated with onshore response work activities. In response to this request, teams of NIOSH personnel evaluated practices and procedures including wildlife cleanup operations, beach cleanup operations, and decontamination and waste management activities throughout the states of Louisiana, Alabama, Mississippi, and Florida. In contrast to the offshore evaluations, which relied on traditional industrial hygiene exposure assessment methodologies and quantitative exposure monitoring to identify potential hazards, the onshore assessment relied on qualitative assessment techniques, including the use of professional judgment and expertise during observations of onshore work activities. Health symptom surveys, however, were similar to those used for the offshore evaluations. The goals of the NIOSH HHE assessments were to describe acute health effects, evaluate occupational exposures in qualitative or quantitative assessments, and generate hypotheses regarding symptoms potentially related to work activities. These assessments were not intended to describe or investigate potential long-term or chronic health effects. The results of these investigations were reported in a series of nine interim reports and report summaries posted on the NIOSH website. The full reports were distributed electronically to key contacts for each work activity evaluated. Included in the reports were conclusions regarding the extent of hazards and exposures identified as well as recommendations for improving workplace conditions. Furthermore, all exposure and health symptom survey data were compiled in electronic spreadsheets and posted on the NIOSH website. This information can be accessed at http://www.cdc.gov/niosh/topics/oilspillresponse/gulfspillhhe.html
. Additional information about other components of the NIOSH Deepwater Horizon response activities outside of the HHE investigation, including response worker rostering efforts, analyses of injury and illness data, and guidance and educational materials developed for the response can be found on the NIOSH website at http://www.cdc.gov/niosh/topics/oilspillresponse/
. This final report summarizes our evaluations made during the course of the offshore and onshore HHE investigations and describes the conditions and characteristics encountered during the event. Overarching conclusions and recommendations drawing from the entirety of the HHE investigations are also presented.