Single-use breathalyser

One single-use chemical breathalyser: an inflatable bag connected to a tube containing reactive crystals. It indicates whether a limit has been exceeded, without giving a precise numerical reading.

Wait at least 20 to 30 minutes after your last sip before blowing: residual alcohol in the mouth completely distorts the result. Break both ends of the tube, connect it to the bag, and blow in one go until the bag is fully inflated. Then empty the air from the bag through the tube and read the colour change of the crystals. The result should be read within two minutes.

In France, the maximum level is 0.5 g of alcohol per litre of blood, or 0.25 mg per litre of exhaled air. But it drops to 0.2 g/l for drivers on a probationary licence and for public transport drivers, which in practice amounts to near-zero tolerance. Check which one applies to you before relying on a test.

Is a chemical breathalyser reliable?
It gives an indication of whether a limit has been crossed, not a measurement. It is affected by blowing technique, temperature and the expiry date. Treat a negative result as a clue, never as a guarantee.

Is there an expiry date?
Yes, it is printed on the tube, and it matters: the reactive crystals degrade. An expired breathalyser is worthless.

Can it be reused?
No, it is single-use. The chemical reaction is irreversible.

How long does it take for alcohol to be eliminated?
Elimination is slow, around 0.10 to 0.15 g/l per hour, and it is not sped up by coffee, a shower or water. Nothing replaces time. If in doubt, do not drive.

Alcohol abuse is dangerous for your health. Please drink responsibly. Sale to persons under 18 is prohibited.