In our previous post, we discussed the methods that are available for testing blood alcohol concentration. One of these, the Breathalyzer test is the most commonly used. That is due to the ease of use. Blood tests must only be done in a clinical or hospital setting. These tests are much more invasive than a breath test, so many police departments rely on breath tests to determine a person's BAC.
While the Breathalyzer is the most convenient method of determining BAC, it isn't the most accurate. There are several different factors that can affect the BAC result of a Breathalyzer test. One of these factors is the type of sensor that is used in the equipment.
Generally, a semiconductor sensor is only suitable for home or personal use. These sensors are associated with false positives that are due to certain conditions. A false positive might be possible because of cigarette smoke, certain chemicals, breath acetone and naturally-occurring ketones.
A more accurate sensor is the fuel cell sensor, which is suitable for professional use. While semiconductor sensors might provide a false positive for people who are on a low calorie diet and those who are diabetic, the fuel cell sensor isn't associated with those false positives. Fuel cell sensors are made for high-level performing.
It is critical that you learn about the technology that is being used in a breath test so that you can let the officer know if there is anything that might make you test positive when you should test negative. You should also know that you have the right to refuse to take the breath test, but that choice is subject to certain consequences that you should carefully consider.
Source: BACtrack, "Are Breathalyzers Accurate?," accessed Dec. 22, 2015