Page 16 - November December Issue
P. 16
Elite Investigative Journal
How Do Breath Machines Work?, pg 16-21
©2014-2015 Press Enter Resolve, LLC
How Do Breath
Machines Work? By Jim Wigmore
Photo Courtesy of commons.wikimedia.org
Whenever I am asked that question I am reminded of a rhyme we used to teach on the police
breath technician training course at the forensic laboratory in Toronto:
Roses are red
Breathalyzers are green
It is an instrument
Not a machine
Breath alcohol testing instruments scientiically measure the air concentration and are not ma-
chines like a tractor. Breath alcohol testing is one of the oldest of the forensic sciences as stud-
ies were published as early as 1867. Currently there are 3 main types of detectors or sensors
found in the evidential breath alcohol testing instruments used by the police to test suspected
drinking drivers; infrared( IR), electrochemical (EC) and a combination of the two.
Basic Principles of Breath Alcohol Testing
Once alcohol is consumed, it diffuses rapidly from the stomach and small intestines into the
blood. The blood containing the alcohol is pumped throughout the body by the heart and dis-
tributed throughout the body according to the water content. Since alcohol is volatile when the
blood passes through the lungs, alcohol will appear in the breath in a concentration relative to
the blood alcohol concentration (BAC).
Comparison of Breath and Blood Alcohol Concentrations
The ratio employed by evidential breath alcohol instruments in the US, Canada and many other
countries is 2100:1, which tends to result in breath test results that are on average 10% lower
16
How Do Breath Machines Work?, pg 16-21
©2014-2015 Press Enter Resolve, LLC
How Do Breath
Machines Work? By Jim Wigmore
Photo Courtesy of commons.wikimedia.org
Whenever I am asked that question I am reminded of a rhyme we used to teach on the police
breath technician training course at the forensic laboratory in Toronto:
Roses are red
Breathalyzers are green
It is an instrument
Not a machine
Breath alcohol testing instruments scientiically measure the air concentration and are not ma-
chines like a tractor. Breath alcohol testing is one of the oldest of the forensic sciences as stud-
ies were published as early as 1867. Currently there are 3 main types of detectors or sensors
found in the evidential breath alcohol testing instruments used by the police to test suspected
drinking drivers; infrared( IR), electrochemical (EC) and a combination of the two.
Basic Principles of Breath Alcohol Testing
Once alcohol is consumed, it diffuses rapidly from the stomach and small intestines into the
blood. The blood containing the alcohol is pumped throughout the body by the heart and dis-
tributed throughout the body according to the water content. Since alcohol is volatile when the
blood passes through the lungs, alcohol will appear in the breath in a concentration relative to
the blood alcohol concentration (BAC).
Comparison of Breath and Blood Alcohol Concentrations
The ratio employed by evidential breath alcohol instruments in the US, Canada and many other
countries is 2100:1, which tends to result in breath test results that are on average 10% lower
16
