Most employers understand the dangers of having intoxicated workers on-site. But what about the day after? Even when an employee’s Blood Alcohol Concentration (BAC) is back to 0.00%, they may still be impaired — and that’s a risk many Australian workplaces overlook.
In safety-critical sectors like construction, mining, transport, and aviation, next-day alcohol impairment could be the invisible trigger behind costly mistakes, near misses, or serious incidents.
Understanding next-day alcohol impairment
Also known as residual impairment, this refers to the after-effects of alcohol that linger even once intoxication has worn off. Common symptoms include:
- Headaches and nausea (classic hangover symptoms)
- Disrupted sleep or ongoing fatigue
- Mental fog, poor concentration
- Slower reflexes and impaired decision-making
According to a study published in the Journal of Clinical Medicine (2020), hangovers can lead to increased absenteeism and workplace conflict, as well as reduced productivity and alertness — even if no alcohol remains in the bloodstream.
This is particularly important in Australia’s high-risk industries, where a momentary lapse can cause injury, damage, or even loss of life.
RELATED: Drunk driving vs Driving with a hangover
Why a 0.00% BAC isn’t the full story
Breathalysers are designed to detect alcohol still present in the body — not the after-effects. That means an employee may return a zero reading and still be unfit for duty.
Symptoms of next-day impairment include:
- Slower reaction times
- Mood swings or irritability
- Foggy thinking or forgetfulness
- Poor decision-making
In roles involving vehicles, machinery, or precision tasks, these symptoms can significantly compromise safety.
What does the law say?
Under Australia’s WHS legislation, employers have a legal duty of care to provide a safe work environment. That responsibility includes managing fitness for work — even if a worker is not technically intoxicated.
If an incident occurs and it’s linked to next-day alcohol impairment, employers may face:
- Fines or prosecution under WHS laws
- Reputational damage
- Loss of contracts or licensing
- Higher insurance premiums
It’s no longer enough to assume a passed breath test equals a safe worker.
How to manage next-day impairment
A truly effective alcohol safety program should go beyond testing and include:
- ✅ Wellness and fatigue checks at the start of shifts
- ✅ Manager training to identify subtle signs of impairment
- ✅ Post-event reminders after Friday knock-offs, Christmas parties, or long weekends
- ✅ Supportive culture, encouraging honest conversations about readiness for work
Education is just as important as enforcement — and prevention starts before the problem walks through the door.
Tools that support smarter alcohol safety
Breathalysers are still a crucial part of any workplace alcohol policy. Andatech offers AS/NZS 3547:2019 certified models like the Prodigy S, ideal for workplace screening.
But remember: 🧠 A 0.00% reading doesn’t mean a worker is performing at 100%.
Residual symptoms — fatigue, fogginess, slower reflexes — aren’t detectable by breathalysers. That’s why workplaces need both tools and policies that address impairment beyond the number.
Final thought: Go beyond the BAC
Breathalysers help keep intoxicated workers off-site — but they can’t detect a hangover.
To truly protect your team, take a broader approach. Combine certified testing tools with education, proactive check-ins, and a safety-first culture that recognises the real risks of next-day impairment.
READ MORE: What to include in your drug and alcohol testing policy
