SGS Galson is committed to keeping you informed of industry changes that affect how you do your jobs. These changes are often related to changes in exposure limits by industry governing bodies or the government itself. To keep your clients in compliance, you need to stay up to date, which is not always easy. We can help.

As you may know, the American Conference of Governmental Industrial Hygienists (ACGIH) publishes booklets that list Threshold Limit Values (TLVs) for each controlled substance relative to worker exposure. Although the U.S. follows OSHA’s Permissible Exposure Limit (PEL) standards, it’s important that our clients in Canada, as well as those providing services to either global companies or companies outside the U.S., are informed about ACGIH updates.


Recently, ACGIH published a Notice of Intended Change (NIC) to benzene, lowering the limit 25 times of the current listed level. Specifically:

  • Time Weighted Average (TWA) – proposed change from 0.5 ppm to 0.02 ppm (25x lower)
  • Short-Term Exposure Limits (STEL) – proposed change from 2.5 ppm to 0.1 ppm (25x lower)


The good news is that SGS Galson can meet most of these new requirements at no additional charge.

  • Assay Badges – we can meet the TWA on 525 only – 0.017 ppm RL at 480 minutes; we cannot currently meet the STEL
  • Pump and tube – we can meet the STEL and the TWA only if exceeding method-recommended 30L max – 0.021 ppm @ 30 L, 0.018 ppm @ 35 L
  • TO17 & TO15 – we can meet both the TWA and STEL


A few other compounds that we analyze are also going on the ACGIH NIC list: 

  • Iodine – TWA: 0.01 ppm IFV to 0.001 ppm IFV – Method recommends 5-minute sampling; STEL: 0.1 ppm to 0.01 ppm IFV – 15 minutes @ 0.5 LPM gives 7.5 L for which our RL is 0.024 ppm. We are looking into new methods to be able to meet the limits and will keep you updated.
  • Nitric acid – STEL is noted as going from 4 ppm to 0.025 ppm IFV. Using 7907, 15 minutes @ 2 LPM gives 30 L for which our RL is 0.062 ppm. We are also looking into new methods to be able to meet the limits and will keep you updated.
  • Vinyltoulene – is noted as going from 50 ppm to 10 ppm TWA. For 480 minutes, our RL on 566 badge is 0.51 ppm. The method-max 24L gives RL of 1.7 ppm. We can meet these new requirements


SGS Galson will keep you informed and deliver the results you need to keep your clients in compliance. Please contact me or our award-winning client service team with your questions on ACIGH protocols or anything else we can help you with.


We are looking into new methods to be able to meet the limits and will keep everyone updated.

Ed Stuber, CIH, ROH, FAIHA
Industries & Environment
Portfolio Lead, Industrial Hygiene
SGS Galson
Mobile: +1 315 671 3926
Follow me: LinkedIn


We are SGS – the world’s leading inspection, testing and certification company.

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