A copycat?

I’ve been accused of being a copycat: http://www.lampworketc.com/forums/showpost.php?p=1909634&postcount=14

IT was adopted on ISGB forum first by Vince, than Mike copycatted it. It’s the specification for industrial class A fume hoods…..

Ummm…no, sorry Dale, but you are incorrect. Both Vince and I use the ACGIH (American Conference of Governmental and Industrial Hygenists http://www.acgih.org/home.htm ) recommendations for ventilation systems from their “Industrial Ventilation: A manual of Recommended Practice”. There is no “copycatting” going on here, just the usage of an internationally recognized organizations recommended practices. It is unfortunate that Dale chose to use the wording he did as it denigrates the work I do on behalf of lampworkers around the world. Continue reading

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Chemical exposure, decoding the limits

When talking about exposure to hazardous chemicals, the safety industry has developed some acronyms that make it difficult to understand what the actual exposure limitations are.

ppm: parts per million

OSHA: Occupational Safety and Health Administration http://www.osha.gov/

NIOSH: National Institute for Occupational Safety and Health http://www.cdc.gov/niosh/

ACGIH: American Conference of Governmental Industrial Hygenists http://www.acgih.org/home.htm

TWA: Time Weighted Average. The averaged exposure to a chemical over certain period of time (usually 8 hours for OSHA).

PEL: Permissible Exposure Limit. Usually provided in either ppm or in a concentration such as mg/M³ (micrograms per cubic meter) over an 8 hour TWA.

STEL: Short Term Exposure Limit. Provided in either ppm or in a concentration such as mg/M³ (micrograms per cubic meter) over a short term time period such as 15 minutes. This is also a TWA (time weighted average).

REL: Recommended Exposure Limit. This is purely a NIOSH term that takes into account OSHA data as well as “real life”, and sets a limit at which health and life may be affected for exposures beyond the REL.