This revision was mainly introduced to implement the
European Union changes to the Indicative Occupational Exposure Limit Values
(IOELVs). This has involved the introduction of New Workplace Exposure Limits
for certain substances (e.g. Isopentane) and removing others (e.g. Pyrethrins)
as well as numerous amendments. To make it simple to see what’s changed, the
Book has a foreword, which details the changes made both in 2007, and in 2011.
There is one thing, however, that I would like to point out, which is of note
and isn’t mentioned in the foreword!
It actually only relates to Sulphuric Acid mist, which has
been added in this revision, and it is listed like this:
|
Substance
|
CAS No.
|
8-Hour TWA WEL (Mg.m3)
|
Comments
|
|
Sulphuric acid (mist)
|
7664-93-9
|
0.05
|
The mist is defined as the thoracic fraction
|
This is the first time in the UK that the requirement for
thoracic fraction sampling has been introduced. In other words, there is a
completely different way to have to sample for it! As of yet, the HSE have not
introduced a method specifically for the UK, although I’m sure there will be
one. In the meantime, if you have the need, then we have to look to the US
where thoracic fraction sampling is a regular activity.
Just for the refresher – the thoracic fraction comprises
particles with a size of less than 30 microns, so larger than the Respirable
dust we are used to sampling for in the UK with the likes of the SKC cyclone.
If anyone needs to sample for Sulphuric Acid mist, then get
in touch as we can sort you out the relevant sampling heads and media. For anyone
else, this could be an indication that thoracic sampling may well be adopted
for other substances in the future, so keep your eyes peeled, watch out for my
updates, and if you need further training, click on the link below and check
out one of our courses.
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