The basic purpose of any respirator is, simply, to protect the respiratory system from the inhalation of hazardous atmospheres. Respirators provide protection either by removing contaminants from the air before it is inhaled or by supplying an independent source of respirable air. This respiratory protection program not only must follow Occupational Safety and Health Administrations (OSHAs) guidelines but must also be well planned and properly managed. A written respiratory protection program that complies with OSHA regulations is designed to do all that is possible to protect those employees whose job duties require the use of respirators. A standard respiratory protection program provides standards for respirator fit testing. The goals of respirator fit testing are to provide employees with a face seal on a respirator that exhibits the most protective and comfortable fit, and to instruct employees on the proper use of respirators and their limitations. The three levels of fit testing are initial, annual, and pre-use self-testing.