Circular breathing does not help a person avoid or “beat” a breathalyzer, and it cannot lower a result. Breath-testing laws and device design anticipate unusual breathing patterns, and officers are trained to deal with irregular blows.
Circular breathing is a technique musicians use to produce a continuous, unbroken stream of air, allowing them to play wind instruments without pausing to inhale. It looks like they’re breathing in and out at the same time, though that’s not exactly what’s happening.
A person fills their cheeks with air while still exhaling from the lungs. When the lungs are nearly empty, they push the air stored in their cheeks out through the mouth. This creates a brief, steady airflow even though they aren’t actively exhaling from the lungs. While the cheeks are pushing air forward, the person quickly inhales through the nose to refill the lungs. As soon as the lungs are refilled, airflow switches back from cheek-pressure to regular exhalation.
As a matter of physiology and device mechanics, however, circular breathing can pose a problem in your breathalyzer test. Sometimes, the more air you blow, the higher you reading can be.
Circular breathing can cause an invalid or incomplete sample. Circular breathing involves pushing air from the cheeks rather than the lungs. Approved screening devices (ASDs) and evidentiary breathalyzers require deep-lung air (“alveolar air”), because that air reflects blood alcohol concentration.
Cheek air or shallow breath can lead to “Insufficient sample” messages, or errors in collecting the requisite volume or flow rate. Failure to register any result can result in a refusal allegation.
The machine senses this type of breathing. It will not give a BAC unless it detects proper flow, volume, and temperature that match a deep-lung sample.
It might look to the officer like you’re attempting to interfere. Most police officers treat irregular blowing as a failure or refusal, an attempt to circumvent the test, and sometimes even grounds for additional investigation or charges.
Circular breathing can make the airflow inconsistent, which can be interpreted as non-compliance.
It does not reduce the alcohol content of the sample.
Even if someone momentarily pushes cheek air, the device requires sustained flow. As soon as alveolar air arrives, the reading most closely reflects the person’s blood alcohol concentration.
Breathalyzers have features to prevent manipulation including minimum volume thresholds, flow-rate sensors, temperature sensors, and more modern ones even have algorithms that reject non-alveolar breaths.
The device simply waits until all criteria are met.
Circular breathing also could delay the test, which has legal consequences. You are required to provide a breath sample immediately.
If an officer believes the person is “playing games” with breathing, the result may be a recorded refusal with immediate penalties.
The last thing you should try to do if asked to provide a breath sample into a roadside breathalyzer or a breathalyzer at the police station is take any steps to attempt to defeat the test. You’re better off challenging the validity of the result or its admissibility at trial than you are trying to figure out how to avoid a consequence while dealing directly with the police.