Page 17 - November December Issue
P. 17
How Do Breath Machines Work?
than the actual BAC. All breath testing instruments are designed to obtain a deep lung sample as a puff or “poor
blow” will result in an even lower breath alcohol concentration, as seen in Table 1, based on drinking male and
female drinking subjects using the Intox EC/IR. The blood sample and breath sample were collected nearly
simultaneously.
Breath Blood Breath Blood
Test Test Test Test
0.112 0.134 0.114 0.142
0.092 0.107 0.084 0.096
0.133 0.153 0.066 0.083
Table 1: Comparison of breath (Intox EC/IR) and blood alcohol concentrations in drinking subjects
Mouth Alcohol Effect
The major potential problem of breath alcohol testing is the mouth alcohol effect. If a person has placed any
substance containing alcohol in their mouths, a false high breath result can be obtained if a breath test is con-
ducted within 10 – 15 minutes. This is seen in Figure 1, based on my own research Typically a deprivation/ob-
servation period of approximately 15 minutes is observed before a evidential breath test is conducted to prevent
this false high result.
In addition to the deprivation/observation period, breath testing instruments based on IR detection have mouth
alcohol detectors which are an additional safeguard against the mouth alcohol effect. The third safeguard is by
conducting 2 separate breath tests several minutes apart with good agreement (usually within ±0.02 g/100mL).
Figure 1: The mouth alcohol effect in an alcohol-free subject after rinsing the mouth with an alcoholic
beverage
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than the actual BAC. All breath testing instruments are designed to obtain a deep lung sample as a puff or “poor
blow” will result in an even lower breath alcohol concentration, as seen in Table 1, based on drinking male and
female drinking subjects using the Intox EC/IR. The blood sample and breath sample were collected nearly
simultaneously.
Breath Blood Breath Blood
Test Test Test Test
0.112 0.134 0.114 0.142
0.092 0.107 0.084 0.096
0.133 0.153 0.066 0.083
Table 1: Comparison of breath (Intox EC/IR) and blood alcohol concentrations in drinking subjects
Mouth Alcohol Effect
The major potential problem of breath alcohol testing is the mouth alcohol effect. If a person has placed any
substance containing alcohol in their mouths, a false high breath result can be obtained if a breath test is con-
ducted within 10 – 15 minutes. This is seen in Figure 1, based on my own research Typically a deprivation/ob-
servation period of approximately 15 minutes is observed before a evidential breath test is conducted to prevent
this false high result.
In addition to the deprivation/observation period, breath testing instruments based on IR detection have mouth
alcohol detectors which are an additional safeguard against the mouth alcohol effect. The third safeguard is by
conducting 2 separate breath tests several minutes apart with good agreement (usually within ±0.02 g/100mL).
Figure 1: The mouth alcohol effect in an alcohol-free subject after rinsing the mouth with an alcoholic
beverage
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