Breath Test After Airbag Deployment.
Dr. Ronald Henson was kind enough to share this with us.
The Tyndall Effect is at issue for drivers involved in accidents in which the air bag device was deployed. The Tyndall Effect, discovered by John Tyndall, a British physicist in the 1800s, is the suspension of insoluble particles (colloidal suspension) in liquid or gases. The effect is a dispersion of light. Like headlights in the fog, the light emitted from the headlight is not shown directly through the fog to a road sign. Instead, the fog (colloid) disperses the light. In relation to airbags and breath alcohol testing, a person exposed to airbag deployment can produce an erroneously high breath alcohol reading using infrared technology machines.
The airbag is deployed (at 200 m.p.h.) using a nitrogen gas to fill the airbag in about 30 milliseconds. The powdery substance seen during deployment and on an individual’s clothing is talc and/or cornstarch packed with the bag to maintain the bag’s integrity while stored in place. When the talc and cornstarch are deployed into the air with the airbag inflation, the particles are inhaled and will be expelled in the breath for several hours. Individuals have reported regurgitating and spitting out the powdery substance for two to three hours and more. Andreas Madlung, The Chemistry behind the Airbag: High Tech in First-Year Chemistry, 73 J.Chem.Educ. 347 (1996).
When an individual then blows into a breath machine using infrared analysis like the Intoxilyzer Model 5000, the talc and/or cornstarch is introduced with the breath sample into the breath analysis chamber. When the infrared light is shown through the chamber, the light is then dispersed because of the Tyndall Effect. Thus, the reading is high erroneous when attempting to qualify and quantify for ethyl alcohol. When the Intoxilyzer Model 5000 was first released in the early 1980s, the airbag/Tyndall Effect was not a likely issue due to a lack of airbags in vehicles. However, with the mandates for airbags and expansion of their usage within the vehicle, the Tyndall Effect is a major factor in BrAC accuracy. Blood testing is the appropriate method to combat the Tyndall Effect.
Ronald Henson, Ph.D., CPCT
P.O. Box 10706
Peoria, IL 61612-0706