When properly fitted, helps provide respiratory protection from mercury vapor or chlorine at concentrations up to 10 times the Permissible Exposure Limit (PEL) with half facepieces or 50 times PEL with full facepieces. Full facepieces must be quantitatively fit tested to claim assigned protection factor above 10 in negative pressure mode. Not for use in environments that are immediately dangerous to life or health (IDLH). Note: The mercury vapor end of service life indicator must be readily visible without manipulation when wearing the respirator. If not readily visible, do not use.