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Bryan60  
#1 Posted : 20 November 2012 16:36:46(UTC)
Rank: Forum user
Bryan60

Hi All,

Trying to get my head round this one. (new to me)

If employees are working with solvent with a 15 min STEL, how many periods can they work for in a 6 hour day and what break period must be taken after each 15 minutes of exposure.

Thanks in advance for any help.

Bryan
Clairel  
#2 Posted : 20 November 2012 16:46:41(UTC)
Rank: Super forum user
Clairel

I think you've misunderstood what a STEL is.

Short Term Exposure Limit - which is measured over 15 mins. So it doesn't have a STEL of 15 mins it will have a maximum exposure limit over any 15 minute period. So you need to know how much they are exposed to over that 15 minute period. The only way to do that is to do some air monitoring.

But if they are using a susbstance that has a STEL then really you should be looking at controlling exposure so that they are not meeting that STEL at all. The substance no doubt will also have a TWA exposure limit (that is the maximum they can be exposed to over an 8 hr period).

What are they doing and what are they using?

Bryan60  
#3 Posted : 20 November 2012 16:53:29(UTC)
Rank: Forum user
Bryan60

They are using a solvent based joint filler mixed with sawdust to fill the gaps between old timber floorboards in a heritage project prior to sealing over. The TWA on the MSDS states 500.00 ppm, 1210.00 mg/m3 over an 8 hr period.

Hope this helps.
Clairel  
#4 Posted : 20 November 2012 17:04:33(UTC)
Rank: Super forum user
Clairel

What is the STEL?

The reality of the situation is that most people will make a value judgement based on what they are using and how they are using it and for how long they are using it. From that they decide what controls to put in place and whether they need to monitor exposure.

If they are not spraying the chemicals and it is not long duration then the chances are they are not exceeding the limits. But you need to look at how they are working (ie, leaning over the fumes) and ventilation levels in the room.

If you are doing this is different locations then it may well be impossible to determine if they are exceeding the exposure limits as the variables will change (ventilation for example).

Judgement call. Or monitor one job and if you are way in exceeding then take a view as that being an average job and act accordingly.
Bryan60  
#5 Posted : 21 November 2012 10:55:24(UTC)
Rank: Forum user
Bryan60

This is a one off job. I have decided to ensure all PPE is used and will continuously monitor it. Thanks for your input Clairel.

Cheers
Bryan
Barrie(Badger)Etter  
#6 Posted : 22 November 2012 10:44:59(UTC)
Rank: Super forum user
Barrie(Badger)Etter

Try this link from archives: http://forum.iosh.co.uk/?g=posts&t=94739 from Chris Packham, it may help with visulisation of a loe STEL15.

bADGER
Bryan60  
#7 Posted : 22 November 2012 15:07:35(UTC)
Rank: Forum user
Bryan60

Thanks Barrie,

Makes intersting reading.

Cheers,
Bryan
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