Document 3QX9qZ8y9eyBMeVyD0bok2dZJ

Page 2253 1 It is an average concentration over a 2 workday. There can be peaks and valleys in the 3 exposure, but the idea is to try to maintain that 4 average at some value. 5 The time weighted part comes in like this. 6 If you collect a number of samples over a 7 workday and some samples are longer in duration than 8 others, for example, if one sample is half hour and 9 another sample is an hour, you would give more weight 10 in the weighting process to the longer sample, so it 11 is a process of coming up with this average 12 concentration over a workday. 13 Q So from 1946 until -- I guess you said it 14 was 1968 that the notice of intent to change the TLV 15 was published, but it wasn't actually changed until 16 '70 or '71; is that right? 17 A The notice of intent stayed on the books, of 18 course, this one usually was two years, and I think it 19 was a little over two years for this one. 20 Q So in that time period if a worker had a 21 peak exposure that was in excess of the five million