Are Breathalyzers Accurate?


Are Breathalyzers Accurate?

In the US, it is illegal to drive a car with a blood alcohol content of 0.08% or higher. Yet, driving under the influence of alcohol or other intoxicating substances remains a major problem in America with over 50,000 fatalities happening each year. Being able to test blood alcohol content or 'BAC' quickly and with accuracy is extremely important. Taking a blood sample in the field for it to be tested in the laboratory is not efficient or practical for detaining drivers suspected of DUI. That is where Breathalyzers come in.

What are Breathalyzers?

A Breathalyzer is a simple device that is used to estimate the blood alcohol content (BAC) from a breath sample. Alcohol being volatile evaporates from the blood and enters the alveolar airway. Hence, the concentration of alcohol in alveolar air way is proportional to the concentration of alcohol content in the blood. There are three types of Breathalyzers used:

1.Semiconductor Oxide-based/Color-changing Breathalyzer (uses a mixture of chemicals which react with alcohol and produce different colors which signifies BAC)

2.Fuel Cell Breathalyzer (fuel-cell technology helps to determine BAC by the strength of the electrical current produced)

3.Infrared Breathalyzer or Intoxilyzer (uses the infra-red spectrum to detect intoxication by identifying molecules based on how they absorb IR light)


In the US, Breathalyzers are used by law enforcement officials to screen drivers at DUI checkpoints or if suspected of driving under the influence. If a driver's BAC measures above the legal limit, they will be arrested and charged with DUI. The Breathalyzer has also gained popularity outside the realm of the legal system. Many drivers public to test themselves at the source of alcohol consumption. These are used in restaurants, charities, pubs, weddings, and all types of licensed events.


Since the Breathalyzer may help an officer establish probable cause for a DUI arrest, it needs to be accurate. Just like a vehicle needs frequent maintenance to guarantee the proper functioning, all Breathalyzer devices - whether for personal or professional use - need calibration to ensure accuracy. With time, they begin to display inaccurate results if they are not properly maintained regularly. For this purpose, the equipment needs to be sent to an accredited Breathalyzer Recalibration Lab such as the CIH Equipment Company, Inc.

Factors Affecting Breathalyzer Accuracy

The accuracy of the Breathalyzer may be affected by several factors. Some of the factors are as follows:

Calibration: Breathalyzers need to be recalibrated frequently, usually once every six months. Many hand-held Breathalyzers use a silicon oxide sensor which is susceptible to contamination and interference. These sensors need to be recalibrated or replaced frequently.

Interfering Compounds: Some natural substances such as acetone are volatile and may be falsely identified as Ethyl alcohol in some Breathalyzers.

Environmental products: Some products such as mouth wash falsely elevate the readings of the Breathalyzer like Listerine mouth wash which contains 27% alcohol.


Calibration is a process whereby a trained technician checks and adjusts the internal settings of the Breathalyzer by comparing its test results to a known alcohol standard. This ensures that the sensor is in excellent operating condition and the results are accurate. Also, calibration ensures that all the parts of the device are working perfectly and free of defect, thereby, extending the overall life of the Breathalyzer.

Calibration is not an easy job. It can be done by inexperienced users or without the proper equipment. It must be performed in suitable conditions i.e. temperature, humidity, fixed alcohol content, flow force, etc. The Breathalyzer is set to calibration mode and specially designed pin tools are used to calibrate it. As part of the process, air having the same quality as exhaled air and predefined alcohol content are injected into it. Thus, calibration should be performed in an accredited lab having learned technicians like CIH Equipment Company, Inc.

Breathalyzer Calibration Services

Many companies provide calibration services but CIH Equipment Company, Inc has been a leader in Industrial Hygiene Calibration Services since 1993. We are a team of scientists, technicians, and engineers, whose skills are complimented only by our commitment. Our lab procedures are based on modern techniques from industry standards, government organizations, and professional groups.

Methods of Calibration

There are two methods of calibrating a Breathalyzer -the Wet Bath and Dry Gas methods. Each method requires use of specialized equipment by qualified technicians.

Wet-Bath method uses an ethanol/water standard in a specific specialized alcohol concentration, present, and supplied in specialized breath simulator equipment. This method is expensive and is not portable. The standard must be new and substituted regularly.

Dry-Gas method uses a portable calibration standard which is a specific mixture of ethanol and inert nitrogen present in a pressurized canister. This process is cheaper than alternative methods and requires fewer steps. The apparatus is also portable, as a result, the calibrations can be done when and where required.

Breathalyzer Calibration Gas

As mentioned above, the dry-gas method of calibration requires the use of calibration gas. That’s where EGas Depot comes in providing the exact Ethanol Gas mixture needed for breathalyzer calibrations. EGas Depot supplies a huge variety of high-quality precision calibration gas mixtures for gas detectors, from simple gases, such as highly pure Nitrogen, to complex four-gas mixtures and highly reactive calibration gas mixtures.

A Service You Can Count On

Accurate and timely Breathalyzer calibration is very important to its functioning and even plays a part in whether or not the BAC measurements taken from a suspected drunk driver will be held up in court. If the instrument has not been properly maintained by receiving regular, well-documented calibration services - it could be argued in court that the results provided by the breathalyzer cannot be proven accurate. Consequently, breathalyzers must be sent to certified labs for calibration. CIH Equipment Company, Inc is the best choice as they have more than 25 years of experience. Their team consists of experienced laboratory personnel who provide fast, accurate, and hassle-free calibrations. Besides, you can benefit from the services of EGas Depot, a division of CIH Equipment Company, Inc which provides the Breathalyzer calibration gases. EGas Depot provides exceptional quality products and services at extremely competitive prices. They are highly efficient and ship all the orders within 1-3 business days.

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