Only the Occupational Safety and Health Administration (OSHA) permissible exposure limits (PELs) are legally enforceable in the United States. Some of the OSHA PELs are based upon outdated toxicology studies and may not be protective enough. The American Conference of Governmental Industrial Hygienists (ACGIH) publishes threshold limit values (TLVs). Many of the TLVs are much more stringent than the corresponding OSHA PELs based on more recent studies and the fact that the TLVs can be updated much more frequently than the PELs. The National Institute for Occupational Safety and Health (NIOSH) also publishes guidelines called recommended exposure limits (RELs). OSHA is not allowed to use TLVs or RELs specifically to issue citations. Discuss how you believe an industrial hygienist should approach the use of PELs, TLVs, and RELs in controlling exposures at a workplace. Explain how you would recommend controlling exposures for a chemical when no occupational exposure limit (OEL) has been established.