Advanced Industrial Hygiene

Several organizations publish occupational exposure limits (OELs) including the Occupational Safety and Health Administration’s (OSHA) permissible exposure limits (PELs), the American Conference of Governmental Industrial Hygienists’ (ACGIH) threshold limit values (TLVs), and the National Institute for Occupational Safety and Health’s (NIOSH) recommended exposure limits (RELs). Only OSHA’s PELs are legally enforceable.

Discuss why you would only use the OSHA PEL at a facility where you were the safety officer, or alternatively, why you would choose to use one of the other OELs or a combination of the OELs.

(Again, this is a trick question. To ignore an ACGIH or NIOSH OEL when evaluating workplace exposures is not an option for the IH Professional. That being said, there are times when the ACGIH or NIOSH OEL may not apply to the type of exposure or work process we are monitoring. Also, be aware that some chemicals such as lead have both PELs and vertical standards with action levels which add to the factors influencing your review of workplace exposures (see

Please include the name of the person or question to which you are replying in the subject line. For example, “Tom’s response to Susan’s comment.”


If I were the Industrial Hygienist on site I would use the OSHA PEL because it is the only legally binding results, so these are the numbers that the company must maintain or be under.  It would be nice to use the threshold limit values because they are usually lower than the OSHA PEL and could make for an even cleaner healthier environment for everyone.  The only issue with using the TLV is trying to convince management of the benefits when by law they can have higher levels that fall within the OSHA PEL.  Management would probably say you are being too conservative and it is not necessary to require values that are under the recommended limits set by OSHA PEL.  I think since there is already a limit set in place with the values that you must not exceed, that we should just use the legally binding OSHA PEL limits, that’s not to say that we will just blindly follow these limits foreve, we will do our do diligence and studying the effects of these limits in the employees to make sure we continue to give them the cleanest and healthiest work environment free from hazards.



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