There are a lot of misconceptions floating around regarding what a breathalyzer can measure, what the results mean, and who does or does not need one. In order to squash some of the misinformation, we here present the top five breathalyzer myths.

Myth #1. “You can beat a breathalyzer by hyperventilating, exercising, or holding your breath before you blow.”

This is an interesting one because it’s partly true. An often-cited, decades-old study found that hyperventilation and vigorous exercise did indeed lower subjects’ BAC readings by as much as 10%. Conversely, holding their breath actually increased subjects’ BAC readings by up to 20%. Unfortunately, these activities can also render one light-headed and gasping for air – behaviour that would undoubtedly capture the attention of law enforcement officers who are already closely examining an individual for being under the influence.

However, there’s another technique used to beat a breathalyzer that is less well known–some people will try sucking instead of blowing into the breathalyzer mouthpiece, therefore drawing air across the sensor from a different direction. This technique, too, is well known to the police, and is the reason why officers often put their palms up behind the unit to ensure breath is coming out in the correct direction.

Myth #2. “I don’t need a breathalyzer – my drinking is under control (or, I don’t drink at all).”

One of the most pervasive misconceptions around breathalyzers is that they are only for people who drink to excess, and that if you can “control” your drinking, then you don’t need one.

This is totally untrue. In fact, even if you are a teetotaler, you will find a breathalyzer useful with friends or family members who do drink.

Here’s why—without a breathalyzer, there is no accurate way of measuring a person’s alcohol intoxication. In fact, the people who think they have their drinking “under control” are sometimes the most jeopardized. People may claim that they know what 0.08% BAC “feels” like, and therefore don’t need to test themselves.

There are several reasons why this is a dangerous idea. First, you don’t always know how much alcohol is in your drink. Alcohol concentrations in beer, wine, and mixed drinks can be deceptive.

Second, even as an experienced drinker, how alcohol affects you changes over time depending on a multitude of factors. As you age, the intoxicating effects of alcohol become increasingly pronounced. As you gain or lose weight, alcohol will affect your differently. If you are taking medication, if you have an empty stomach, or if your ratio of fat to muscle content shifts, you can be affected by alcohol differently from what you are used to.

Lastly, a breathalyzer is not just for you alone—it’s for the people around you, as well. Have you ever been in the party of someone who is obviously drunker than they think they are? Nothing stops a person from making bad decisions quicker than confronting their actual BAC.