Un breathalyzer or breathalyzer is a device for measuring the amount of alcohol (or ethanol) present in the exhaled air. This makes it possible to deduce the quantity of alcohol present in the body.

There are chemical or electronic breathalysers:

• chemical breathalyzer : it is the famous single-use “balloon” in which you have to blow. Above a certain alcohol threshold in the exhaled air, a chemical reagent changes color.
• electronic breathalyzer : the probe produces an electrical signal. Only the tip is unique, the device is reusable.

The result (obtained in milligrams per liter of exhaled air) makes it possible to have an estimate of the blood alcohol level, that is to say of the quantity of alcohol in the blood (expressed in terms of grams per liter of blood).

The breathalyzer can be done on a voluntary basis to control your blood alcohol level in case of doubt. The goal is usually to find out whether or not it is possible to get behind the wheel. In France, since March 2012, it is also mandatory to have a breathalyzer in all motor vehicles.

The police can also use a breathalyzer to check a driver’s blood alcohol level, for example following any violation of the Highway Code but also as part of preventive checks.

Remember that driving under the influence of alcohol remains the leading cause of death on the roads.

It is important to read the instructions for use carefully before using your own breathalyzer.

Also check the expiry date and make sure beforehand that this model is certified by the government (NF standard in France). The list of manufacturers of breathalyzers certified in France can be consulted on the website of the National Metrology and Testing Laboratory (LNE).

On chemical breathalysers, you sometimes have to break the plastic ends of the test tube before blowing. It is important to wait at least 20 minutes after consuming the last glass of alcohol before using the breathalyzer.

It is then necessary to inhale deeply and exhale to inflate the “balloon” in an exhalation.

The use of electronic breathalysers is similar: a disposable mouthpiece is placed on the device and blown directly into it, until the sound or visual signal stops. The value is displayed on the screen.

Please note that electronic devices must be calibrated frequently (once a year) to be valid.

The breathalyzer will determine whether a person is fit to drive after consuming alcohol.

In the case of the chemical breathalyzer, if the crystals in the tube remain yellow, the test is considered negative. It is possible to take the wheel.

Conversely, if the crystals turn green, the blood alcohol level is above the legal limit and you cannot drive.

As a reminder, in France, it is forbidden to drive with an alcohol level in the blood greater than 0,5 g / L, i.e. 0,25 mg of alcohol per liter of exhaled air.

In Quebec, the rate must be less than 0,8 g / L, but it must be zero for new drivers and young people (under 21).

In the event of a police check, if the breathalyzer is found to be positive, the blood alcohol level will be checked either by breathalyzer (which is the only legal instrument to measure the precise alcohol level in the exhaled air with a view to taking action. legal), or by an exceptional blood test.