Posted By Steffan Jones I'd appreciate some help with the following... Is there any simple way of estimating whether a WEL is likely to be exceeded through use of a particular substance? For example; I am trying to assess the risk of a substance which contains a small amount of Methanol (LTEL 266mgm-3 and STEL 333mgm-3). We would only use millilitres of the substance for approximately 2 minutes 3 times a day... Is there a general rule of thumb that can be followed or do I need to conduct some form of monitoring in order to determine specifically whether we are likely to exceed the WEL. This would surely mean monitoring would have to be conducted for any substance with a WEL...can that really be the case? Many thanks, SJ

Posted By Steffan Jones Thank you for the advice.

Posted By stephen d clarke Hi, Agree with above postings, if you know the actual amount of methyl alcohol that could evaporate and the volume of the room you should be able to make a rough estimate. 3M do a respirator selector and odour threshold table at: http://www.lbl.gov/ehs/c...iratorSelectionGuide.pdf But smell really depends upon personal sensitivity, usually quite a broad range. Steve