Breath Alcohol

AuthorJames G. Wigmore
breath Alcohol
Breath alcohol analysis is commonly used in law enforcement as it has
many advantages over blood alcohol testing:
• Breath alcohol testing is noninvasive. No needles are required to
collect blood; hence, there is no possibility of injury or transmis-
sion of disea se.
• The breath alcohol results are known im mediately, as opposed to
the several days or even weeks needed for blood results to be re-
ported by forensic laboratories. The police are therefore immedi-
ately aware of what charge to lay and whether medical treatment
may be required for the drink ing driver (e.g., alcohol poisoning).
• Breath alcohol correlates better with brain a lcohol concentration
(arterial blood) and gives a better indication of impairment due to
alcohol duri ng the rising blood alcohol concentration (BAC) pha se.
• There are no continuity or storage and transpor tation issues. The
breath sample is provided directly into the breath alcohol instr u-
ment. No special blood tubes, swabs, identity seals, biohazard
refrigeration, or special transportation is required, as for blood
• No medical staf‌f or phlebotomists a re needed for breath alcohol
analysis. The breath tests may be conducted at the police station
or mobile van, allowing the time bet ween the arrest and testing
to be reduced signif‌icantly.
• There is no problem with a real or alleged blood or needle phobia
of the arrested driver.
Breath Alcohol
Reference Number: 
This chapter deals w ith the many issues that arise in cr iminal court,
such as the ability to provide a suitable breath sample, the blood-breath
ratio (BBR), the mouth alcohol ef‌fect, and the specif‌icity of breath alco-
hol tests.
Breath alcohol detection technology has changed dramatically over the
more than  years since the Breatha lyzer (using a wet chemical method)
was f‌irst introduced (, ). The chemical reaction that was the
basis of the Breathalyzer was based on potassium dichromate (a yellow-
orange color) and sulfuric acid reacting with alcohol to form chromic
sulfate (a blue-green color), potassium sulfate, acetic acid, and water as
Cr(SO) + KSO+ CHCOOH +   HO
Electrochemical (fuel cell) sensors (–) also convert alcohol
into acetic acid but measure the electric current generated rather than
a colour change, as with the Breatha lyzer. Other devices use infrared
(IR; –) or a combination of the IR and fuel cells () to detect
breath alcohol. The n-type semiconductor (Taguchi) detector has been
found not to be suitable for evidential or even screening applications
(). Future methods of detection of alcohol may include portable
mass spectrometry (MS; ) or full IR spectrum scan (). The
dif‌ferences between two successive breath tests and the truncation of
breath test results are also di scussed in this section (–).
Reference Number: 
, ..,  .. . “The Breathalyzer and Its Applications.”
Medicine Science and the Law, : –,  ( f‌igures,  references)
Abstract: The Breathalyzer, the most successful a nd widely used instr u-
ment for the medicolegal determination of alcohol in the breath, was
designed and developed by R.F. Borkenstein in . It was based on the
photometric measurement of the decrease in yellow color of potassium
dichromate solution in reaction with alcohol.
Wigmore on Alcohol
Reference Number: 
The oxidation of alcohol using acid dichromate forms the basis of most
of the available methods for the determination of alcohol. A degree
of specif‌icity for certain react ants is obtained through the choice of
conditions. Using KCrO in % by volume HSO at ºC or at room
temperature with a suitable catalyst, alcohol is quantitatively oxidized
to acetic acid within  seconds. Variations in acid concentration (plus
or minus %) or time (between  and  seconds) do not appreciably
alter the results. The instrument autom atically compensates for varia-
tions in the KCrO content of the solution.
Reference Number: 
, .. “The Accuracy Reliability and Validity of the Breathalyz-
er.” Australian New Zealand Journal of Criminology, : –,  (
tables,  references)
Abstract: In this study,  male subjects consumed  mL/kg of % v/v
(volume of solute per volume of solvent) ethanol mixed with lime juice.
Drinking wa s to be completed within  minutes. To prevent nausea,
subjects were allowed to eat a few dry biscuits. T hirty minutes after the
subjects f‌inished drinking, a breath sample was taken from each, and
 minutes later a blood sample was taken. The BAC range was .–
.g/mL. The correlation (r) between blood and breath was ..
A second breath sample was taken in  subjects as close as possible
to the taking of the blood sample. The greatest time dif‌ference was 
minutes. The correlation with blood was .. The largest false high
dif‌ference was a Breathalyzer result of .g / mL and a BAC of
The results of this experiment indicate that the B reathalyzer can be a
reliable instrument in assessing a perso n’s BAL [blood alcohol level]. It is
true that the apparatus was operated under ideal phy sical conditions by
a highly skilled police ocer and that the breath samples were collec ted
from co-operative subjects who h ad drank relatively low quantities of
Reference Number: 
, .., .. , .. ,  .. . “Electrochemical Meas-
urements of Blood Alcohol Levels.” Nature, : –,  ( f‌igure,
 references)

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