Abstract: A chemical impairment detection system adaptable for use in a vehicle. The impairment detection system includes an intake adapted to receive an air sample from a source and an alcohol sensor for detecting an alcohol level in the air sample. An integrated breath chamber channels the air sample from the intake to the alcohol sensor. Source evaluator means in the breath chamber measure one or more characteristics of the received air sample for validating the sample. The source evaluator means measures the air sample characteristics as the air sample flows through the breath chamber.