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Author: Subject: Dust Contamination
DrP
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[*] posted on 27-1-2006 at 08:45
Dust Contamination


If I said that the average dust contaminant level in a building was 0.14mg/m3 - can anyone relate/convert this to a T.W.A. 8hr mg/m3 equivalant value?

Thanks.
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[*] posted on 29-1-2006 at 06:54


Yes, but answering that question needs more information. How long is the shift?
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[*] posted on 30-1-2006 at 01:31


They do 8 hour days approximately.
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[*] posted on 30-1-2006 at 11:32


The easy answer is to send you to this site.
http://www.hse.gov.uk/coshh/calcmethods.pdf

However, if the exposure is roughly constant (ie the people are doing the same job all day) and the shifts are 8 hours, then the TWA is the same as the instantaneous level ie (in this case 0.14mg/m3).

If you are unsure what you are doing then it's probably better to get in a consultant occupational hygienist that to gamble with exposure. (And, in case you wondered, no- I'm not one touting for business). They will not only be able to do the calculation for you but to offer help in reducing it.
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[*] posted on 31-1-2006 at 01:52


Thanks alot.

We have had people in and the figure they gave us for a contaminant level was 0.14 mg/m3. The TWA limits for the powders the guys use is : Total 10mg/m3 and Respirable 4 mg/m3. They then go on to say in their report that the dust levels are 'unacceptable' and we need to install a new extraction LEV device (costing around £10K). I think they are just trying it on so they can sell us a £10K LEV set up. However!!, I really want to make sure. Thanks for your help and the link.
We are currently looking into ways of reducing the dust levels by using less fine powders, maybe damping them down as well, using better repiratory masks and as a last resort - the LEV system.

Regards.


[Edited on 31-1-2006 by DrP]
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[*] posted on 31-1-2006 at 12:27


At the risk of being frighteningly dull for anyone else reading this. Do you know whether the substance was given a MEL or OES?
If it's a MEL then the rule used to be (and they have changed the terms so I'm not sure if this still applies) that levels should be reduced "so far as reasonably practical"- even if the level is below the MEL.
Even then, for a relatively low level, that's a lot of dosh.
What (if it isn't some grave secret) is the stuff you are working with?
You might even want to talk to the local HSE inspectors about this. OTOH HSE's policy is always that masks are the last resort. (Ppe in general is a lousy way to deal with a problem because it's not very reliable and you often have a devil of a job getting people to use it).
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[*] posted on 1-2-2006 at 04:10


Quote:
[quote unionised]
At the risk of being frighteningly dull for anyone else reading this


:D

Hmmm yes - sorry to anyone else reading this. I wasn't sure if this topic was relavant for this forum as it is not really interesting amateur chemistry. However, your comments and suggestions unionised have been a great help to me. I would assume anyone else would just not bother reading once they see what we are talking about. :D


To answer your question:

We use an assortment of powders - as far as I am aware they arn't MEL's. The main dusts are from - Dolomite, TiO2, Huntite and Hydromagnesite. We use LOTS of others too but these are the main bulk powders that generate dust. There is nothing which is classed as a carcinogen or anything nasty.

I called them to see what they ment on their report when they said we were over the WELs. The reading they took at the lip of the mixer whilst a bag of dolomite was being lobbed into it was ~20 mg/m3. In my opinion, even with extraction, the reading at the lip of the machine whilst powder is being loaded will always read high - the ambient average is 0.14 and I rekon that is more relavant for an 8 hr TWA. Therefore we are getting quotes for a continued personal sampling test, where the test kit is situated on the shoulder of the workers.
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[*] posted on 1-2-2006 at 13:34


"Therefore we are getting quotes for a continued personal sampling test, where the test kit is situated on the shoulder of the workers. "
Probably very sensible- for just the reasons you give.

Anyway, the original question might be of interest to others playing with chemicals at home and trying to see if they are poisoning themselves
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[*] posted on 10-4-2008 at 07:50


Oh this is great!! The other year these people tried to sell us this LEV system for £10K+. They insisted it was absolutly nessessary for the H&S of our workers due to the dust level readings they took in the factory (Which as I explained above were biased as they took the readings as the powders were being poured from the bags into the machines). Not convinced by this blatent attempt to sell us equipment we didn't need, I arranged for personal sampling to be done. Over the next 3 months (!!!!) they kept calling to chase their quote to see when they could come down and install their system - each time I requested the results of the personal sampling we had paid for and they kept putting off sending us the results. In short - when they finally realised I wasn't going to purchase this equipment without getting the personal sampling results back first, they sent the results, which showed clearly we did not need their expensive kit after all.

NOW!!!! the plot thikens - 2 years on they are back to do routine checks (always a good thing) - but this time their angle/sales pitch is thier concern for the enviroment (our extractors go out into the open air). I'm convinced these guys are crooks! If what they are saying is true then why didn't they pick up on it 2 years ago when they were trying to con us from a different angle!. They are blatently just trying to sell us their expensive LEV buy using scare tactics with regard to H&S.

Anyway -- I'm biased - what do you think - are they crooks! (our H&S people are too scared to challenge anything anyone says if they mention the buzz words 'enviroment' or 'Health & Safety') - I will get an independent opinion.


(Just to let you know - I am in no way interested in cutting corners when it comes to H&S - if it needs doing we will spend whatever money it takes to ensue worker safety and a clean environment - I just want to make sure it is nescessary!)

[Edited on by DrP]
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[*] posted on 10-4-2008 at 10:11


If these salesmen are being so pushy and shady about about
getting you to buy their equipment, maybe you should also
be skeptical about the equipment they are trying to sell you.
From reading what you wrote above, I get this sinking
feeling that the expensive equipment they are trying to
sell you likely is overpriced, poorly built, and doesn't work
nearly as well as the sales pitch would lead you to believe.
Buying from them might be the start of a long-term relationship
as the salesmen will keep coming back to sell all sorts of
upgrades and improvements but will make themselves scarce
when the shoddily-built equipment breaks and you
demand a replacement.

Quote:

They are blatently just trying to sell us their expensive LEV
buy using scare tactics with regard to H&S. . . .
our H&S people are too scared to challenge anything anyone
says if they mention the buzz words 'enviroment' or 'Health & Safety'

Obviously, they expected that they would be pitching their spiel
to some ignoramus who had been spoonfed horror stories on the
evening news and expected that they all they needed to do was
drop a few buzzwords to look like experts and then push the right
buton to make a sale.

Quote:

Anyway -- I'm biased - what do you think - are they crooks!

As you see, I'm also biased in pretty much the same way.
After one too many experiences with high-pressure sales
tactics, hidden charges, hype-filled advertising (which usually
has little or no information about the product being promoted)
and similar gimmickry which seems to have become the norm
of how business is done today, I have developed quite a bias
against any company which feels the need to promote its
products and services in such a manner. I would rather buy
from a company which spends less on marketing and more
on making a high-quality product which can be sold on its own
merits.

Quote:

I am in no way interested in cutting corners when it comes to H&S

I would consider buying crap from hucksters as one ow the worst ways
to cut corners. Not only would it lkely not actually do much to make
anyone safer, but it would give the false impression that they are safe.
Rather, the way to ensure real safety is to go to reputable dealer.
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[*] posted on 10-4-2008 at 11:15


DrP, if you want an independent opinion you could always ask the HSE.
http://www.hse.gov.uk/contact/
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[*] posted on 11-4-2008 at 07:08


Thanks - we will either try them or just get a second opinion from another company. I just needed to rant about it to get it off my chest the other day.
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