It is well proven that there is a direct correlation between a person’s blood alcohol concentration and his breath alcohol contents. Breath alcohol testing measures the alcohol level of the body, which is exhaled by normal breathing. It is a simple and non-invasive technique.
Nowadays there are a wide range of instruments for measuring breath alcohol. They can vary from disposable screening testers and hand-held devices to the modern and more expensive digital read-out breath alcohol monitors used by police departments and laboratories.
A common tester has a balloon and a glass tube with yellow crystals; the crystals turn green when they get in contact with alcohol molecules. Calibrated alcohol testers are also available to check a person’s alcohol level.
How do they work?
With the chemical test, a person exhales into the balloon with one continuous breath. The balloon’s mouthpiece is fitted to the end of the glass tube. The alcohol content of the exhaled air is measured by counting the number of bands in the tube that have changed from yellow to green. This reflects the alcohol content of the blood.
With a calibrated alcohol tester, the person blows into a mouthpiece or straw, and the device displays the alcohol level digitally. This is more accurate than the balloon type breathalyzer test and uses either infrared (IR) spectroscopy or fuel cells to detect the amount of alcohol present.
See a more detailed explanation of the different types of breath alcohol testers.
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