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How does a Breathalyzer work?

Most residents of Lackawanna County are aware that local police departments use a device called a "Breathalyzer" to measure the blood alcohol content of persons believed to be driving under the influence of alcohol, but very few understand how such devices work. While details vary depending on the model, most Breathalyzers operate on the principles outlined below.

Contrary to the expectations of most people, Breathalyzers do not directly measure the amount of alcohol in a person's bloodstream. That can only be done by taking a blood sample and subjecting it to laboratory analysis. Instead breathalyzers perform a chemical analysis of the person's breath and use that result to calculate the person's BAC.

The person must first breathe into the breathalyzer's analysis chamber. The chamber contains a fuel cell consisting of two platinum electrodes that are separated by a material that is porous to electrolytes. When the exhaled breath enters the fuel cell, the platinum oxidizes the any alcohol present and creates electrons and protons. The result is an electric current that is measured by the breathalyzer.

Scientists have calculated the chemical relationship between the amount of current and the amount of alcohol in the BAC and determined that the strength of the current is directly proportional to the amount of blood in the bloodstream. The operator can read the meter on the breathalyzer and determine whether the suspect's BAC exceeds the legal limit of 0.08 percent.

All drivers in Pennsylvania are required to submit to a blood-alcohol test when requested to do so by a police officer. A refusal to take the test usually results in the suspension of the suspect's driver's license for one year. Anyone who has questions about blood-alcohol tests in Pennsylvania may wish to consult an attorney who is experienced in representing persons accused of Driving Under the Influence of Alcohol.

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