Document vBEj6RYMwqNkDDGBOX2vMjY96
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
j
\
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
1.5 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
i
19 was a little over two years for this one.
,
20 Q So in that time period if a worker had a
1
21 peak exposure that was in excess of the five million
i