“Ambient Fail” exception messages during breath testing of suspected impaired drivers using the Intoxilyzer® 5000C: a 10-year retrospective analysis

Abstract

A retrospective analysis of the incidence of the “Ambient Failed” exception message (AFM) generated by the Intoxilyzer® 5000C was conducted during breath testing of suspected impaired drivers over a 10-year period. The incidence of an AFM occurred in only 2.5% (n = 531) of the 21,016 drivers that were tested. Breath tests containing two AFMs (n = 21; approx. 0.1%) were even less frequent. There was no main effect in the incidence of AFMs attributable either to year (p = 0.83), location of testing (p = 0.72), or to use of different instruments (p = 0.59). Additionally, there was no evidence of alcohol, or other interfering substances, in the ambient conditions that may have falsely elevated either the calibration checks or the subject breath test results. The occurrence of an AFM was associated with elevated blood alcohol concentrations (BACs) compared with BACs from test records that did not contain an AFM. The mean (± standard deviation) BAC from breath test records that contained at least one AFM and from those that did not was 208 mg/100 mL (± 68) and 150 mg/100 mL (± 54), respectively. Ambient conditions needed to generate an AFM during breath testing are transient in nature and the triggering of an AFM is more likely to occur in subjects with elevated BACs.