Do roadside breath tests provide reliable results?

If you have been pulled over by law enforcement on suspicion of drunk driving in North Carolina, you know first-hand the overwhelming feelings that often accompany the situation. You may have been asked to take a roadside breath test as part of the stop.

Officers use roadside breath tests to determine a driver’s blood alcohol content level. However, breath test readings may not produce reliable results, especially when compared to an actual blood test. In some cases, these erroneous results could lead to a wrongful DUI charge and conviction.

How do breath tests work?

When you exhale a breath sample into the breath test device, the machine detects the amount of ethanol present in the sample. It then converts this number to a BAC level without measuring your blood at all. Research from the State University of New York at Potsdam found that the BAC level obtained from breath test readings could vary by more than 15% when compared to one obtained from an actual blood test.

What factors can alter results?

Studies show that the machine picks up substances that have similar molecular structures, which can be found in a number of products and substances. Different types of food and medication have these methyl structures. For example, some people may blow a .05 reading on a breath test after eating bread.

Other factors that can affect breath test readings include the following:

• Fumes from paint, paint remover, cleaners or gasoline
• Pollution or dirt in the air
• Electrical interference from police radios or cellphones
• Relative temperature and humidity of the air

Each person may have varied results based on the oxygen saturation level.

When pulled over by an officer, it is important to know all of your options and rights to minimize the risk of getting wrongfully charged with drunk driving.