How Breathalyzers Work and Their Inherent Limitations
A breathalyzer is a device designed to measure the concentration of alcohol in a person's exhaled breath, which is then used to estimate their blood alcohol concentration (BAC) [1.6.1, 1.6.4]. Modern devices commonly use one of two technologies: infrared (IR) spectroscopy or fuel cell sensors [1.6.2, 1.6.3]. In IR devices, a beam of infrared light is passed through the breath sample, and the amount of light absorbed by alcohol molecules is measured [1.6.2]. Fuel cell technology involves a chemical reaction where alcohol in the breath sample generates an electrical current, with the strength of the current being proportional to the alcohol concentration [1.6.2].
Despite their widespread use, these devices have several limitations [1.6.1]. Their accuracy is highly dependent on proper and regular calibration [1.2.4, 1.6.2]. An improperly maintained or calibrated device can produce unreliable results [1.2.5]. Furthermore, breathalyzers are designed to measure deep lung air (alveolar air), and if the sample is contaminated by alcohol from the mouth or stomach, the reading can be artificially inflated [1.6.5, 1.8.4]. This contamination is known as "mouth alcohol" and is a primary source of error [1.4.4].
Medications That Interfere with Breathalyzer Readings
A significant factor in what throws off a breathalyzer is the use of certain medications, both over-the-counter (OTC) and prescription [1.3.3]. Many liquid medications, such as cough syrups (e.g., Nyquil, Robitussin), cold and flu remedies (e.g., some Vicks products), and allergy medications (e.g., Benadryl), contain alcohol as a solvent or active ingredient [1.3.2, 1.3.5]. When consumed, this alcohol can lead to a false positive reading [1.3.2].
Asthma medications, particularly those delivered via an inhaler like Albuterol, are another major concern [1.3.4, 1.4.5]. These medications can contain compounds that are structurally similar to ethyl alcohol or contain alcohol-based propellants [1.4.6, 1.9.2]. When inhaled, the medication can remain in the airways and be detected by a breathalyzer, potentially leading to a falsely high BAC reading even if the person has not consumed any alcoholic beverages [1.3.4, 1.4.5]. Oral pain relievers like Anbesol, which contain alcohol to numb pain, can also be oxidized by saliva and produce a high reading [1.2.5].
Medical and Physiological Conditions
Certain medical conditions are well-documented to interfere with breathalyzer tests.
Gastroesophageal Reflux Disease (GERD)
GERD, or acid reflux, is a condition where stomach contents flow back up into the esophagus [1.8.1]. If a person with GERD has consumed alcohol, undigested alcohol from the stomach can travel up into the esophagus and mouth [1.8.2, 1.8.3]. When this person exhales into a breathalyzer, the device measures these alcohol vapors from the stomach, not just the deep lung air, leading to an artificially inflated BAC reading [1.8.4]. Even burping or hiccuping can bring up stomach gases containing alcohol, which can skew test results [1.2.4].
Diabetes and Ketogenic Diets
Both diabetes and low-carbohydrate, high-protein diets (like the Keto diet) can cause the body to enter a metabolic state called ketosis [1.2.5, 1.7.3]. In ketosis, the body burns fat for energy instead of carbohydrates, producing byproducts called ketones [1.7.2]. One of these ketones is acetone, which is chemically similar to isopropyl alcohol [1.7.1, 1.7.2]. Many breathalyzer devices, particularly older or portable models, cannot distinguish between the ethyl alcohol found in drinks and the isopropyl alcohol produced during ketosis [1.7.1, 1.7.3]. This can result in a false positive reading for someone who hasn't been drinking at all [1.7.1]. Additionally, symptoms of hypoglycemia (low blood sugar) in diabetics, such as confusion and dizziness, can mimic signs of intoxication [1.2.5].
Other Factors That Can Skew Results
- Mouth Alcohol: This is one of the most common causes of false positives [1.4.4]. It can result from using alcohol-containing mouthwash or breath sprays, which can leave residual alcohol in the mouth for 15-20 minutes [1.3.6, 1.4.4]. Dental work, such as dentures or braces, can also trap alcohol particles [1.2.5].
- Environmental Contaminants: Exposure to fumes from paints, lacquers, cleaning fluids, gasoline, and other volatile organic compounds (VOCs) can lead to false positives [1.2.4, 1.9.3]. People who work with these substances may inhale fumes that a breathalyzer can mistake for ethyl alcohol [1.9.5].
- Certain Foods: Some foods can cause false readings through fermentation in the mouth or stomach. These include very ripe fruit, energy drinks, protein bars, and foods containing yeast like bread and pastries [1.5.1, 1.2.2]. Foods made with alcohol-based extracts, like vanilla, can also leave trace amounts of alcohol in the mouth [1.5.1].
- Device and Operator Error: As mentioned, a lack of proper calibration is a major issue [1.2.6]. Additionally, radio frequency interference (RFI) from police radios can affect electronic devices [1.2.5]. Inexperience or lack of training on the part of the officer administering the test can also lead to procedural errors and inaccurate results [1.2.4, 1.2.5].
| Factor Category | Specific Examples | Mechanism of Interference |
|---|---|---|
| Medical Conditions | GERD (Acid Reflux) [1.8.1], Diabetes [1.2.5], Hypoglycemia [1.2.5] | Regurgitation of stomach alcohol; production of ketones (acetone) mistaken for ethyl alcohol [1.7.2, 1.8.2]. |
| Medications | Asthma Inhalers (Albuterol) [1.3.4], Cough Syrups (Nyquil) [1.3.2], Oral Gels (Anbesol) [1.2.5] | Contain alcohol or alcohol-like compounds; medication lingers in airways [1.3.5, 1.4.5]. |
| Dietary Factors | Keto/Low-Carb Diets [1.7.3], Energy Drinks [1.5.1], Fermented Foods [1.5.2], Ripe Fruit [1.5.4] | Produces ketones; contains trace amounts of alcohol; fermentation in the mouth [1.5.1, 1.7.2]. |
| Mouth Contaminants | Mouthwash [1.3.3], Breath Sprays [1.3.4], Dental Work [1.2.5] | Introduces "mouth alcohol" not from the bloodstream, leading to falsely high readings [1.4.4]. |
| External/Technical | Improper Calibration [1.2.6], Radio Frequency Interference [1.2.5], Occupational Fumes (paint, solvents) [1.2.4] | Equipment inaccuracy; misinterpretation of non-alcoholic chemical compounds [1.9.3, 1.2.4]. |
Conclusion
While breathalyzers are a key tool in enforcing drunk driving laws, they are far from infallible. A wide array of pharmacological, physiological, and environmental factors can significantly skew their results. Medications like asthma inhalers, medical conditions such as GERD and diabetes, popular diets like keto, and even the use of common products like mouthwash can all lead to a BAC reading that does not accurately reflect a person's level of impairment [1.2.1, 1.3.1]. The reliability of a breathalyzer test is also contingent on the machine's proper calibration and the officer's adherence to strict testing protocols [1.2.4, 1.6.2]. Acknowledging these potential interferences is essential for a fair assessment of sobriety.
For more information on the science behind breath testing, you can review this article from the National Institutes of Health: Alcohol breath testing - PMC
