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  • Stephen Biss

Reliability: Ambient Interferents


Tip 48: The reliability of the alcohol standard in a wet-bath #duisimulator may be compromised by the presence in the breath room air of an interferent, that the approved instrument confuses with ethyl alcohol. In the same way that ambient ethyl alcohol can raise the zero baseline, so can an ambient interferent. Interferents may include paint, cleaning fluids, fingerprint cleanup fluids, and chemicals on the clothing or breath of the accused or the qualified technician.

Greater research needs to be done on the subject by scientists at the Centre of Forensic Sciences, by the Alcohol Test Committee, and by scientists in private practice. Further inquiries need to be made of the manufacturer as to the exact bandwidth of the IR filters on the 8000C.

This video is NOT expert evidence. It is provided as an aid to defence counsel in understanding the problem of chemical "interferents" in evidentiary breath testing generally, and wet-bath #duisimulator cal checks specifically. We need to discuss these issues and obtain better answers from the scientific community.

The following data was used during argument in R v O and was filed as part of Exhibits 2 and 9 on the Application. The data was originally filed in R v H at Brampton. The data reveal that the instrument, 80-003779 at Mississauga, flagged an "interferent detect" message during stand-alone calibration checks. Unless the alcohol standard from the lab or the #duisimulator cleaned/rinsed/lubricated by a QT was the source of the interferent, the cause of this fail must have been the ambient air in the breath room.

Breath rooms frequently contain cleaning equipment associated with fingerprinting. The following is an image captured in a Cambridge breath room by the professional photographer hired by the defence in R v G. Notice the reference to D-Limonene under First Aid Treatment.

#interferent #ambientfail #reliability #tip

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