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BAC Test: What It Is And Its Purpose

30 August, 2023

A woman blowing to a breathalyser

A BAC test is a process of measuring Blood Alcohol Concentration or a person’s alcohol level. The BAC is the amount of alcohol present in the bloodstream as measured by a breathalyser or blood test. The purpose of this test is to determine the person’s intoxication or degree of impairment. It helps police officers check if a driver is under the influence of alcohol or drugs and can be used as evidence in court.

Driving while intoxicated poses significant risks to road safety. An impaired driver often has a reduced ability to control the vehicle, leading to accidents and injuries. Thus, law enforcement conducts roadside breath testing to check for alcohol consumption. It is also used in healthcare and workplace settings for various reasons. This article will talk about the processes to measure the BAC, its uses, and the factors affecting the result.

What Is BAC Test?

A BAC test measures the blood alcohol level in a person through a sample of their breath, blood, urine, or saliva. When a person drinks alcohol, small portions pass through the small intestines to the bloodstream. The blood distributes alcohol molecules into different organs, such as the lungs, heart, and salivary glands. The rest goes to the liver to be broken down.

The BAC is calculated in grams of alcohol per 100 ml of blood or 210 litres of breath. It is generally expressed as a percentage known as the BAC level. For example, a BAC of 0.05 means your blood has 0.05% alcohol by volume. Therefore, it represents the ratio of breath alcohol to blood volume.

BAC levels vary from person to person, based on individual factors. These include gender, age, body weight, metabolism, and the number of standard drinks. Hence, two people are unlikely to have the same BAC despite drinking the same type or amount of alcoholic beverage. The effects may also vary, depending on a person’s tolerance level. Thus, a blood alcohol test is a reliable way to determine a person’s intoxication.

Types Of Test Methods

  • Breath test: measures the breath alcohol to blood alcohol ratio (1:2100). It requires a person to blow through a breathalyser. The, the device analyses the breath sample to estimate blood alcohol content.
  • Blood test: it involves taking a blood sample and analysing it in a laboratory. It is the most accurate method as it examines alcohol content directly from the blood.
  • Urine test: this method uses the urine-to-blood ratio of 1.33:1 to measure the BAC.
  • Saliva test: it involves collecting a saliva sample to calculate the BAC. It can detect alcohol for 12 to 24 hours after consumption.

A police officer holding a breathalyser

Purpose Of BAC Test

The main purpose of a BAC test is to know the impairment level of a person. Law enforcement officials conduct roadside testing to determine driver’s alcohol levels. It gives an objective evaluation of a person’s ability to drive safely. In Australia, the legal limit is 0.05% BAC. Hence, a person is guilty of drink driving if their BAC is equal to or exceeds 0.05.

Another purpose of alcohol testing is to monitor the impairment of individuals in the workplace. It is a standard procedure in high-risk industries to prevent accidents and injuries. For instance, alcohol screening is mandatory for truck drivers and heavy machinery operators. Employees are subject to disciplinary actions if they fail the test.

In addition, it is also used in medical settings. It helps diagnose if a person has alcohol use disorder (AUD). It also helps health professionals to monitor the progress of patients in rehabilitation. Overall, it helps deter individuals from excessive consumption, which poses safety risks on the road and in workplaces.

Benefits Of Testing

Alcohol testing helps to ensure the safety of the public. Police officers conduct these tests to remove impaired drivers on the road. Therefore, it helps minimise accidents that can affect other road users. Likewise, it ensures the well-being of employees. Employers can identify and intervene with individuals who may pose a risk to themselves and others.

Moreover, alcohol testing can have a positive impact on productivity. It reduces absenteeism and poor performance associated with alcohol use. Ensuring the workforce is physically and mentally fit increases efficiency. Additionally, employers may offer treatment assistance to staff struggling with addiction.

Viewing the BAC result in the breathalyser screen

Factors Affecting The Accuracy Of BAC Test

Many factors can affect the BAC test results, depending on the method used. Firstly, the breath test accuracy depends on the type of breathalyser sensor. Breath testers employ two kinds of sensors: semiconductors and fuel cells. A semiconductor sensor is more prone to environmental conditions, such as humidity and temperature. On the other hand, fuel cell breathalysers are more specific to ethyl alcohol and do not react with other substances.

Secondly, the timing of the test can be a crucial factor. BAC levels continue to rise for one to two hours after consumption. If a test is conducted soon, it may not reflect the BAC level accurately. In the case of blood and urine tests, improper collection or storage may cause inaccurate results.

Lastly, the presence of other substances may interfere with the test result. For example, alcohol may interact with prescription drugs, causing the BAC to be higher. Likewise, a person’s health condition like diabetes or kidney disease, can affect the concentrations of alcohol in the body.

Limitations

Alcohol tests have several limitations. Each testing method can detect alcohol for a limited period of time. Alcohol stays in the breath for up to 24 hours, while blood samples have a detection window between 6 to 12 hours. Thus, the time of the test is crucial to assessing the correct levels of alcohol.

Another limitation is the accuracy of the testing device used. For instance, breathalysers need to be periodically recalibrated to maintain sensor performance. Lastly, there is potential for false readings due to external factors. Household products containing alcohol may interfere with the results.

Conclusion

The effects of alcohol can vary between individuals. It can cause severe impairment, including slower reaction time and poor coordination. The BAC test is a reliable way to measure the concentration of alcohol in a person’s system. It provides authorities with an objective measure to enforce laws and protect public safety. Individuals with a BAC over the alcohol limit are subject to legal consequences, such as fines, imprisonment, or alcohol interlocks.

Furthermore, employers use it to ensure safety and promote sobriety in the work environment. The methods include breath, blood, urine, and saliva testing. A breath test is the most non-invasive and cost-efficient procedure. While they are mostly accurate, there are several factors and limitations to consider when conducting them. It is vital to follow the procedures correctly to ensure reliable BAC results. A personal device, like BACtrack, can help individuals avoid the health and safety risks of excessive alcohol consumption.

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