Date: Sat, 4 Dec 2010 07:39:34 +0000
Reply-To: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
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From: "Kohler, Christopher E" <cekohler**At_Symbol_Here**INDIANA.EDU>
Subject: Re: OHSA/NIOSH Permissible limits
In-Reply-To: <AANLkTimx-3P2SS3xzQWcQsV6JGNGdHTTtfHTzc7RWXKj**At_Symbol_Here**>

Here is a nice little summary I use in class. For worker safety it always better to u se the lower thresholds but the OSHA thresholds are the legally enforceable ones.


OSHA (or s tate established) exposure limits are law:

PEL = Pe rmissible Exposure Limits (29 CFR 1910.1000)

=95Bas ed on health factors, economic and technical feasibility.
=95TWA = 8 hour time weighted average
=95STE L = 15 minute Short Term Exposure Limit
=95C = Ceiling Concentration must never be exceeded.

Other expo sure limits are guidelines or BMPs:

NIOSH - National  Institute for Occupational Safety and Health

=95Based on chemical, medical, biological, engineering, trade and other information .

=95REL = Recommended Exposure Limits (10 hr TWA, used for recommending new exposure limits to OSHA)

=95IDLH = Immediately Dangerous to Life and Health (based on 30 min. exposure bu t must exit)

ACGIH = American Conference of Governmental Industrial Hygienists

=95Based on health factors only.

=95TLV = Threshold Limit Value (8 hour TLV-TWA, TLV-STEL, TLV-C, they also esta blish =93Excursion Limits=94 commonly used in emergency response activities = 3 to 5 x TLV for 30 min.)

=95BEI = Biological Exposure Indices (mg/l of  body fluid to be used in biological monitoring)

From: DCHAS-L Discussion List [DCHAS-L**At_Symbol_Here**L IST.UVM.EDU] on behalf of Jim Tung [jimtung**At_Symbol_Here**GMAIL.COM]
Sent: Friday, December 03, 2010 4:22 PM
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: [DCHAS-L] OHSA/NIOSH Permissible limits

Hello, all:

When the NIOSH pocket guide has different permissible limits (NIOSH versus OSHA), which is the better one to follow?

For example, benzene's limit for NIOSH is 0.1 ppm (10 hr workday), while OS HA's limit is 1 ppm (8 hour workday.)

Why the difference? From a legal perspective, which is a better choice?

Thanks in advance for any advice you might give; obviously, any advice peop le might give is non-binding, you're not responsible, legal mumbo-jumbo, bl ah, blah.

Cheers, Jim Tung

Lead Hazardous Waste Coordinator
Obiter Research LLC
Champaign, IL

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