Washington State DUI

DUI Breath Test Laws

WAC 448-16-060
Determining agreement of duplicate breath samples.

Pursuant to RCW 46.61.506 the following method is approved for determining whether two breath samples agree to within plus or minus ten percent of their mean.

(1) The breath test results shall be reported, truncated to three decimal places.
(2) The mean of the two breath test results shall be calculated and rounded to four decimal places.
(3) The lower acceptable limit shall be determined by multiplying the above mean by 0.9, and truncating to three decimal places.
(4) The upper acceptable limit shall be determined by multiplying the mean by 1.1 and truncating to three decimal places.
(5) If the results fall within and inclusive of the upper and lower acceptable limits, the two breath samples are valid.


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