Breathalyzers
Why Breathalyzer
The degree of an individual's alcohol intoxication
is determined by the person's blood alcohol concentration (BAC)
level. The BAC level can be measured using invasive measures (blood
sampling) or non-invasive measures (breath, urine sampling). Breath
testing is the most convenient and practical method to determine
one's BAC level.
Principles of Testing
Alcohol requires no digestion and gets absorbed
from the mouth, stomach and intestine to the bloodstream. When
the blood goes through the lungs, the alcohol permeates from the
blood to air in the deep lung region. The alveoli of the lungs
are small tissue sacs surround by a fine network of capillary
blood vessels, the thin membrane of the alveoli allows alcohol
to enter the air. As alcohol in the alveoli air is exhaled, the
concentration of alcohol can be detected by a breathalyzer.
A Breath Alcohol Concentration (BrAC) is
as accurate as the Blood Alcohol Concentration (BAC). The breath
alcohol to blood alcohol ratio of 2100:1 is used for converting
BrAC to BAC. This means that 2100mg of deep lung air will contain
the same amount of alcohol as 1ml of blood.
Breath Alcohol Testing Technologies
A number of technologies are used to test
breath sample for alcohol:
¡P Gas Chromatography
¡P Fuel Cell
¡P Semiconductor sensors
¡P Infra Red Spectroscopy
¡P Wet Chemistry