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Why are you telling me about CAL/OSHA PEL’s?
Part I Much, Much Lower Worker Inhalation Levels

Barbara Kanegsberg, SQRC

Why are you telling me about Cal/OSHA PEL’s, Barbara? We have an ESH group to take care of all of that. I don’t have to be concerned.

Yes you DO have to be concerned. A new policy from Cal/OSHA and a bill introduced at the State level both signal the likelihood of legally enforceable worker inhalation limits (Permissible Exposure Levels or PEL’s) that are orders of magnitude lower than those currently in use. For example, the PEL for Methylene chloride could decrease from 25 ppm to 0.0058 ppm.

In addition to the obvious impact on profits and on competitive stance, there are potentially serious worker safety, environmental, and product quality impacts. The California climate shift in PEL’s can make it more difficult to assess and act on risks to workers and to protect workers from true hazards in the workplace. In addition, the very low PEL’s can negatively impact the environment and may compromise critical product.

Federal and State PEL’s

As a general rule, the higher the allowable worker inhalation exposure number for a given chemical (the Permissible Exposure Level or PEL), the fewer safety controls a company needs to use. One might think that the lower the level, the greater the worker protection. However, PEL’s have to be realistic to be enforceable.

Legally enforceable PEL’s are set by the Federal Occupational Safety and Health Administration (OSHA). Certainly, we need better overall worker protection throughout the U.S, including protection from inhalation hazards in the workplace. To achieve these goals, PEL’s would preferably be set at the Federal level. However, for a number of reasons, including lawsuits by business, special interest groups, etc., Federal OSHA has been slow to develop new PEL’s.

New in California

States can set lower, legally enforceable PEL’s than those that are set by Federal OSHA.

Cal/OSHA has developed a new PEL policy (1) that has positive aspects. This policy includes goals of transparency and a somewhat standardized decision template. A Health Expert Advisory Committee (HEAC) of volunteers would review the scientific literature, and, where deemed appropriate, recommend new or revised PEL’s. A Feasibility Advisory Committee (FAC) would have informal input to the process.

Impact of OEHHA Risk factors (as in Proposition 65)

The new Cal/OSHA PEL policy could use risk factors based on community safety assessments that have been developed by the Office of Environmental Health Hazard Assessment (OEHHA). Risk factors developed by OEHHA are used as the basis of the Proposition 65 chemicals; a proliferation of warning signs are now found on fabrication facilities, grocery stores, and many other buildings throughout California. However, for industry, a great deal more than signage would be needed in that a quantifiable, legally enforceable worker inhalation number would be generated. Recently introduced legislation (AB 515, Lieber) would require use of the OEHHA risk factors as the basis of PEL’s in most cases (2). Whatever the fate of the legislation, the option to use OEHHA risk factors is clearly indicated throughout the new Cal/OSHA policy.

So how low is low for Cal/OSHA PEL’s ?

Really low. Much, much lower than nationally accepted levels. Here are a few examples (3).

Examples, Potential Cal OSHA PEL’s



Possible CalOSHA PEL

Approx. Magnitude lower in

Methylene chloride
25 ppm (OSHA)
0.0058 ppm
Perchloroethylene (Tetrachloroethylene)
25 ppm
0.00021 ppm
10 ppm
0.0015 ppm
20 ppm
0.19 ppm
25 ppm
0.005 ppm
5 mg/m3 (OSHA)
10 mg/m3 (ACGIH)
0.0001 mg/m3
Ethylene glycol monomethyl ether
0.1 ppm
0.002 ppm
Nickel refinery dust
(pyrometallurgical process)
100 mg/m3
0.08 mg/m3


References and resources
(1) To review the final PEL policy document, go to

(2) To check the status of AB 515 and other legislation in California, go to:

(3) For a more complete and complex table of potential California PEL’s, including the basis of the laborious calculations kindly provided by Ron Hutton, please see Clean Source Volume II, Issue 1.

Thanks: To James Unmack, CIH, for reviewing parts I, II, and III of this article.

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