Document zzy9nzVj3ODe097ROmd7peQnB

1 question, yes. And the answer is it is understood Page 3094 2 that it is unusual for there always to be a constant 3 exposure in almost any environment. 4 If there is a disturbing circumstance where 5 there will be increased levels at one time, there may 6 be some other times when the levels aren't as high, so 7 over the years, and that has evolved over many, many 8 years, the concept of let's measure the most probable 9 average concentration and consider that as the goal to 10 shoot for, so that there may be some periods of time 11 when the concentration is higher, and other periods of 12 time when the concentration is lower, such that the 13 average will represent the desired level with certain 14 excursions above, as long as there is equivalent 15 excursions below. 16 Q Let me ask you this: As a toxicologist and 17 industrial hygienist, do you believe that the 18 differences between the time-weighted average 19 measurements and the peak measurements are important? 20 A Certainly. In certain circumstances they 21 are both very important.