March 2023, Volume 15, Issue 1

20 Years and Counting!

Caliche, Ltd., a Health, Safety and Environmental (HSE) Consulting and Management Firm, is pleased to announce our 20 Year Anniversary. On November 12, 2003, Caliche, Ltd. completed the purchase of Environmental Technologies, Inc. and immediately stated providing HSE professional services throughout Texas, Oklahoma, Louisiana, New Mexico, Colorado, Oregon, Florida, and globally.

Since November 2003, Caliche has opened a 2nd office in Corpus Christi, TX and continues responding to wide range of clients to include oil and gas, manufacturing, hospitals, maritime, schools, and commercial businesses. Our staff looks forward to another 20 years and appreciates all of our clients we have had the opportunity to assist them in protecting people, property and the environment.

“Safety is not an intellectual exercise to keep us in work. It is a matter of life and death. It is the sum of our contributions to safety management that determines whether the people we work with live or die.” – Sir Brian Appleton, safety assessor.

Occupational Exposure Limits - Which one to use?

By Frank M. Parker, III

Confused by all the occupational exposure limits [OELs]? Don’t understand the difference between them? Well, join the crowd. It seems like every organization has their own OELs.

In the United States, at the federal level, we have the Occupational Safety & Health Administration’s [OSHA] Permissible Exposure Limits [PELs], the National Institute for Safety & Health’s [NIOSH] Recommended Exposure Limits [RELs] and Immediately Dangerous to Life and Health [IDLH], the American Conference of Governmental Industrial Hygienist’s [ACGIH] Threshold Limit Values [TLVs], and the Environmental Protection Agency’s [EPA] Acute Exposure Guideline Levels [AEGLs]. There are also OELs established by other national organizations such as the American National Standards Institute [ANSI] as well as by individual state agencies including California, Texas and others. You can throw in the European Union if you have concerns over there. For purposes here we’ll focus on the US federal standards.

OSHA PELs, with a few exceptions [i.e. Asbestos & Benzene] were promulgated in 1968 and haven’t been updated since. In fact, a previous OSHA administrator has publicly stated that the RELs are not protective. PELs are based on exposure concentrations on any eight-hour day. Much like a speed limit, if OSHA inspector determines that your plant has exposed a worker in excess of the PEL you are in violation. There are two PELs, an eight-hour time weighted average [TWA] and a ceiling or short-term exposure limit [STEL]. You must comply with both. OSHA PELs represents the level of knowledge some 50 years ago. Legally you must comply with the OSHA PELs. However, if you are concerned about the health of your work force, OSHA’s PELs are probably not the appropriate OEL.

NIOSH RELs represent a more current state of knowledge than OSHA’s PELs. RELs are exposure standards based on up to a ten-hour TWA and/or a 15-minute ceiling [C] concentration. In addition, NIOSH has an Immediately Dangerous to Life and Health [IDLH] concentration, an emergency escape exposure of up to 30 minutes.

ACGIH TLVs are also much more current than the OSHA PELs. The ACGIH also promulgates two exposure standards – eight-hour TWAs and/or 15-minute STELs.

The EPA’s AEGLs focus on the general public including the young, old and infirm. Generally, the work force contains the healthier segment of our population and the OSHA, NIOSH and ACGIH OELs are the more appropriate standards to rely on.

So, which one should I use? Use the OEL that is based on the most current scientific knowledge. Determining which one is the most current may take some research. If you don’t have research capability, use the lowest value. In my 50 years of industrial hygiene experience no OEL has ever been increased and almost all 1968 OELs have been reduced. Any questions give us a call.

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