Both the Food and Drug Administration (FDA) and the National Institute for Occupational Safety and Health (NIOSH) have responsibilities for evaluating and regulating respiratory protective devices (“respirators”) for health care workers. Respirators protect the user from respiratory hazards by either removing contaminants from the air (air-purifying respirators) or by supplying clean air from another source (air-supplying respirators). Respirators that are used in workplaces in the United States must be approved by NIOSH and meet standards and test results specified by regulation.