> a similarly impairing dose of cannabis results in 0.00001 ppm of the drug in breath.
Would you mind citing a source? My understanding of why this has been a difficult problem thus far is that THC concentration is not inversely proportional to motor function (unlike alcohol). I.e. the drug effects people differently and simply measuring THC concentration alone is not enough to indicate intoxication or lack thereof.
This comment comes from the fact that peak THC impairment occurs 1 hour post consumption (see the NHTSA Marijuana-Impaired Driving, A Report to Congress) and our average measurement at that time for THC in breath is around 0.00001 ppm. With alcohol, the cut off for impairment is 0.08% BAC which correlates to around 200 ppm of alcohol. So concentration of THC at the time of peak impairment is 0.00001 ppm whereas the concentration of alcohol is 200 ppm at the time of peak impairment. We did not mean to say 0.00001 ppm THC = 200 ppm of alcohol. We just wanted to illustrate the magnitude different in detecting both molecules. I guess it was not well worded :(.
Would you mind citing a source? My understanding of why this has been a difficult problem thus far is that THC concentration is not inversely proportional to motor function (unlike alcohol). I.e. the drug effects people differently and simply measuring THC concentration alone is not enough to indicate intoxication or lack thereof.