Section 75 Blowing Technique, Volume, and Flow Rate

• Library: DWI Experts and the Science of Chemical Tests 2014

Because people have different rates, force, and duration of blowing within the accepted criteria range of evidential breath-alcohol testing machines, it has been acknowledged that the normal biological variability for breath-alcohol testing is +/- 0.020 g (grams)/210 L (liter). See Kurt M. Dubowski & Natalie A. Essary, Breath-Alcohol Analysis on Duplicate Samples (1986), Proceedings of the 10^th International Conference on Alcohol, Drugs and Traffic Safety (1987). With a normal biological variability of +/- 0.020 g/210 L, a breath-alcohol test result at the per se level of 0.080 g/210 L has a biological variability of +/- 25%.

A biological variable as high as 0.04% has been found. C. Dennis...