Section 82 Tyndall Effect Defense

• Library: DWI Experts and the Science of Chemical Tests 2014

The Tyndall Effect (diffusion/scattering of light) is a defense that has been asserted when there has been air-bag deployment and a subsequent breath test with a suspected high reading. The defense is based on the particles that were in an aerosol from the air bag and were blown into the sample chamber of the breath-testing machine. The small particles in aerosol reflect, absorb, or scatter the IR light beam and, thus, cause a high reading at the detector. This is similar to how some smoke detectors work. The particles reduce the amount of IR energy reaching the detector, thus causing the high BrAC reading over and above the BAC. Andreas Madlung, The Chemistry Behind the Airbag: High Tech in First-Year Chemistry, 73 J. CHEM. EDUC. 347 (1996).

But direct research is limited; the real Tyndall issues may be stronger with some construction workers and industrial employees that are exposed to silica and other dust. J.H. Brown et al., Influence of Particle Size Upon the Retention of Particulate Matter in the Human Lung, 40 AM...