Law enforcement officers use breath test devices to measure the amount of ethanol alcohol in a driver’s system and determine whether he or she is driving over the legal limit of 0.08. While officers use these devices as an easy way to determine a driver’s blood alcohol level on the side of the road, the results of these machines may not be accurate and reliable. Studies show a significant variance of at least 15% between blood alcohol level readings obtained from breath test devices to the BAC levels received from actual blood tests, according to the State University of New York at Potsdam. 

The variance between the two readings causes at least one in four drivers to show inflated BAC readings. This can result in an innocent person being charged and possibly convicted of a DUI. There are certain factors that may be involved in higher BAC readings from breath test devices. These include the following: 

  • The temperature and relative humidity of the air 
  • Cigarette smoke and gasoline fumes 
  • Residual vomit, blood, drink or food in the mouth 
  • Paint removers and cleaning fluids 
  • Static interference from officer radios or cell phones 
  • Dirt and pollution in the air 

In addition to detecting ethanol alcohol in an exhaled breath sample, breath test devices also pick up structures and substances that have similar methyl groups. It takes this amount and converts it into a blood alcohol level comparable to the level obtained from a blood test. Yet, it is these measured differences that make breath test devices an unreliable source of detecting whether a driver is under the influence of alcohol.