How accurate is a breathalyzer test

A breathalyzer is a means of determining your blood alcohol content (BAC.) After a person blows air into the breathalyzer’s mouthpiece, a chemical reaction takes place which measures the blood-alcohol content. However, how accurate is a breathalyzer when it comes to measuring your BAC?

Some have argued that breathalyzer tests are not accurate and should not be seen as conclusive proof that a driver was under the influence of alcohol. This argument highlights the fact that blood tests or urine samples are actually more accurate than breath tests, but less commonly used.

Breathalyzers estimate BAC based on a breath sample, and will not be as accurate as when a sample of blood is tested for alcohol content. However, fuel cell breathalyzers are highly accurate if calibrated according to the manufacturer’s recommendations. When used correctly, breathalyzers provide a very close estimate of our BAC.

Law Enforcement Breathalyzer

The sensor is the component inside a breathalyzer that reads and interprets your BAC. For personal use there are two types to consider, fuel cell sensors and semi-conductor sensors. For professional use (law enforcement), fuel cells are better at providing both highly accurate and more consistent BAC results.
View Personal Breathalyzer
View Law Enforcement Breathalyzer

So why are breath tests still the most common way to check a driver’s BAC? This is most likely because of the ease of use. It is much simpler (and less expensive) to have a driver blow into a breathalyzer than it is to perform a blood or urine test for a more accurate BAC reading.

Don't forget, as with any testing device, breathalyzers need to be periodically calibrated and have their batteries replaced. Failure to perform this kind of basic maintenance can create inaccurate readings.


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