How does a breath test work?

On Behalf of | Nov 7, 2014 | Drunk Driving, Firm News |

Drivers in Colorado may know that if they are suspected of drunk driving, it is possible they will be administered a Breathalyzer test. This test is used to register the amount of alcohol present in an individual’s blood.

Three categories of technology are used by Breathalyzer tests to measure one’s blood alcohol content. Personal Breathalyzers are oxide-based testers like the BACtrack S50 and S70. The units measure the individual’s BAC level by using an ethanol sensor. They are lauded as being economical and compact while operating with low energy consumption. The semiconductor oxide-based units require calibration after every 300 to 400 assessments or annually.

Another type of Breathalyzer tester involves the use of fuel cells. They are believed to be very accurate and have high sensitivity. The units are both portable and hand-held and are used in more than 30 states for evidence in court. They must be calibrated after 1,000 tests are performed or yearly. The testers include the BACtrack Mobile, BACtrack S75 and S80 Pro as well as the BACtrack Element. The alcohol is oxidized and produces an electrical current, the amplitude of which is based on the amount of alcohol.

Large units such as those found in police stations use spectrophotometer technology. The units measure absorption of infrared light of specific molecules. By identifying ethanol using this method, the alcohol level is provided.

If a driver faces charges of DUI, a Breathalyzer test may be used to substantiate it. Breathalyzer units require calibration to perform effectively. If the equipment is not properly maintained, this may provide inaccurate results. This information is not intended to offer specific legal advice; an attorney may review the evidence presented to support the DUI charge. If proper care of the Breathalyzer unit was not taken, the attorney may challenge its use in court.

Source:, “Frequently Asked Questions“, November 06, 2014


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