BAT Result Interpretation & Analysis 3 — Questions and Answers
Question 1: On a breath alcohol test record, the notation 'AIR BLANK PASS' indicates:
- The subject's ambient air contained no interferents above threshold
- The instrument detected no residual alcohol in its own air path before sampling (Correct answer)
- The observation period was completed without alcohol introduction
- The calibration standard matched the expected target value
Correct answer: The instrument detected no residual alcohol in its own air path before sampling
An air blank purges and checks the instrument's internal air path to confirm no residual alcohol remains from a prior test.
Question 2: Which of the following best describes 'mouth alcohol' in the context of breath testing?
- Alcohol absorbed into the oral mucosa from normal digestion
- Alcohol in the oral cavity from recent drinking, belching, or regurgitation that has not been cleared (Correct answer)
- The alcohol detected in the first portion of exhalation
- Alcohol dissolved in saliva that exits during speech
Correct answer: Alcohol in the oral cavity from recent drinking, belching, or regurgitation that has not been cleared
Mouth alcohol is residual alcohol trapped in the oral cavity that can falsely elevate BrAC if the observation period was inadequate.
Question 3: A subject's two sequential BrAC readings are 0.114 and 0.118 g/210L. What is reported?
- 0.114 g/210L (the lower result) (Correct answer)
- 0.116 g/210L (the average)
- 0.118 g/210L (the higher result)
- The test is invalid because readings differ by 0.004
Correct answer: 0.114 g/210L (the lower result)
When both results are valid (within 0.020 of each other), the lower of the two readings is reported as the official BrAC.
Question 4: What is the primary purpose of the mandatory observation period before a breath alcohol test?
- To allow the instrument to warm up and self-calibrate
- To ensure the subject has not introduced any foreign substances into the mouth that could affect the result (Correct answer)
- To document the subject's physical signs of impairment
- To obtain informed consent from the subject before testing
Correct answer: To ensure the subject has not introduced any foreign substances into the mouth that could affect the result
The observation period (typically 15-20 minutes) ensures mouth alcohol from drinking, belching, or regurgitation dissipates before sampling.
Question 5: Acetone in the breath of a diabetic subject could cause a falsely elevated reading on which type of instrument?
- Infrared spectroscopy instruments operating at the 9.5 micron wavelength (Correct answer)
- Fuel cell electrochemical instruments
- Gas chromatography instruments
- Breathalyzer devices using potassium dichromate
Correct answer: Infrared spectroscopy instruments operating at the 9.5 micron wavelength
Older or poorly designed infrared instruments may mistake acetone's absorption spectrum for ethanol; modern instruments use multiple wavelengths to differentiate.
Question 6: In the context of breath alcohol testing, 'alveolar air' refers to:
- The first breath exhaled from the upper airways
- Deep lung air that has equilibrated with pulmonary capillary blood (Correct answer)
- Air captured from the nasal passages during exhalation
- Residual air remaining in the lungs after maximum exhalation
Correct answer: Deep lung air that has equilibrated with pulmonary capillary blood
Alveolar air from the deep alveoli has directly exchanged gases with blood, providing the most accurate reflection of blood alcohol concentration.
Question 7: A BAT receives a printout showing 'INTERFERENT DETECTED.' Which action is appropriate?
- Record the result and note the interferent warning on the ATF
- Retest immediately without waiting
- Discard the result, document the interferent detection, and note the test was not completed (Correct answer)
- Average this result with a subsequent clean result
Correct answer: Discard the result, document the interferent detection, and note the test was not completed
When an interferent is detected, the result is not a valid BrAC reading and cannot be reported; the BAT must document that the test could not be completed.
BAT Result Interpretation & Analysis 3
On a breath alcohol test record, the notation 'AIR BLANK PASS' indicates: