For air contaminants for which OSHA has not determined a dose or permissible exposure limit, other sources of information, such as Material Safety Data Sheets that comply with the Hazard Communication Standard, section 1910.1200, published information, and internal documents can provide guidance in establishing acceptable atmospheric conditions. Any work involving burning, welding or similar fire-producing operations. Also, any work that produces a source of ignition, such as grinding, drilling, or heating. The minimum concentration of a combustible gas or vapor in air that will ignite if an ignition source is introduced. Any devices or clothing worn by the worker to protect against hazards in the environment.
Examples are respirators, gloves, and chemical splash goggles.
PEL - Permissible Exposure Level Concentration of a substance to which an individual may be exposed repeatedly without adverse effect. The removal of gases or vapors from a confined space by the process of displacement. A person designated by the department head in charge of entry to remain outside the confined space and to be in constant communication with the personnel working inside the confined space. Permit- Required Confined Spaces . U.S. Government Printing Office.