Infrared breath testing is the type of breath testing most commonly used in the Rochester area.

Over the past fifteen years, all law enforcement agencies in the area have discontinued the use of older style breath test machines – which used a chemical process – in favor of machines that rely on infrared technology.

All substances, including alcohol, absorb infrared radiation at different wavelengths.

As a result, exposing a substance to an infrared source and measuring the amount of radiation absorbed at different wavelengths can be used to identify both what a substance is and how much of the substance is present.

Ethyl alcohol is known to have major peaks of infrared radiation absorption at wavelengths of 3.39, 3.48, 7.25, 9.18, 9.50, and 11.5 microns.

No other substance absorbs infrared radiation at those wavelengths in precisely the same manner as ethyl alcohol.

Unfortunately, a breath test machine that is actually capable of measuring absorption at all of these wavelengths would be very expensive.

As a result, nearly all models of infrared-based breath testing machines actually only measure absorption at one of the wavelengths where ethyl alcohol is known to absorb infrared radiation.

Which wavelength is being measured varies among different breath test machine models based on what the manufacturer believes is the wavelength least likely to also be absorbed by other substances typically found on the breath (which would increase the breath test score) and what techniques the manufacturer is using to screen out these other substances.

While not perfect, infrared breath test machines are considered reliable by the courts, and the result of a breath test using such a machine will be admitted as evidence so long as the machine is working properly and the test was properly conducted.

If you need an experienced DWI lawyer who understands the rules surrounding the breath test, call us at 585-484-7432.