Abstract: Moisture may build up inside an alcohol monitor that is securely attached to a human subject due to the inlet air from the subject's skin surface which constantly emits water vapor in the form of insensible skin perspiration. As the warm moist air which has very high humidity flows along the air flow path through decreasing temperatures within the alcohol monitor, moisture will be removed from the air through condensation. The condensation problem is solved by lowering the humidity level in the air sample by mixing the very humid air sample from the body with less humid ambient air, which increases the dew point for condensation. Increasing the dew point in the air sample means that there must be a greater change in temperature along the air flow path of the air sample in order to cause the moisture in the air sample to condense and become water.