In most subjects, BAC was assayed from plasma using an Alcohol analyzer (Analox Instruments, Hammersmith, London). Coefficient of variance for precision is 1–2% and sensitivity is 0.1 mg/dL. In 9 participants in whom plasma was not obtained BAC was estimated from breath using an Alco-Sensor IV Instrument (Intoximeters Inc., St Louis, MO). Correlation of blood and breath alcohol levels was 0.959 (p<0.0001) in 28 participants in which both measures were obtained.
