A long-term NIOSH research effort, The Carbon Nanotube Registry, is dedicated to understanding workplace health risks associated with carbon nanotubes. In the early 2000s, research showed a potential for lung disease in lab animals after exposure to carbon nanotubes. To better understand worker exposures, NIOSH enrolled workers across the United States to participate in the study, asked them questions about their health, and performed onsite health exams at the workplace. This exposure registry will follow workers into the future to help identify chronic diseases that may result from these exposures.