Under DOT rules, an alcohol concentration of 0.04 or greater on a confirmation test is a violation. The employee must be removed from safety-sensitive functions and cannot return until completing the return-to-duty process with a Substance Abuse Professional (SAP) (49 CFR Part 40, Subpart O).

A confirmation result of 0.02 to 0.039 is not a violation of the prohibition, but the employee still cannot perform safety-sensitive functions for a period set by the employer's DOT agency rule. For FMCSA-regulated drivers, that period is at least 24 hours (49 CFR 382.505).

Screening and confirmation

• A screening test below 0.02 is a negative result.
• A screening result of 0.02 or higher requires a confirmation test on an evidential breath testing device, performed after a waiting period (49 CFR 40.251). The confirmation result is the one that counts.

Questions about a specific result or an employee's duty status belong with your DER and, where needed, your legal or program advisor.

How does the breath alcohol test work? · 49 CFR Part 40, Subpart M: Alcohol confirmation tests