Alcohol and effects on driving
Safe driving requires the driver to pay attention to many things at once and to be able to react quickly when something unexpected happens.
All drivers need:
- to be mentally alert;
- to have clear vision;
- physical coordination; and
- the ability to react appropriately.
Impairment of any of these driving abilities can increase the risk of having a crash.
The dangers of driving after using alcohol include that the driver:
- takes longer to react, especially to emergency situations;
- their ability to think clearly is reduced, making it difficult to perform the multiple tasks required in order to drive safely;
- their ability to pay attention is reduced, such as not noticing other road users; and
- may have blurred vision and reduced hearing.
Common effects of alcohol, such as feeling more confident, may also lead to increased risk taking, while effects such as feeling more relaxed may lead to the driver falling asleep at the wheel.
A person who drinks alcohol may think they can alter their driving to counteract any impairment to their driving ability. However, this is a dangerous approach, as the effects of alcohol may mean that the driver:
- fails to notice something they would normally have observed;
- may have an altered view and experience of reality — their actions and responses may be quite different to what is actually needed; and
- may be unaware how much their driving skills are affected after drinking alcohol.
Blood Alcohol Concentration (BAC)
Blood Alcohol Concentration, or BAC, is used to measure the amount of alcohol within the bloodstream. A BAC of .05 means that there is .05 g (or 50 mg) of alcohol in every 100 mL of blood. BAC is measured by analysing a sample of a person's breath or blood.
Women who have had less to drink than their male partners can have a higher BAC, as their body has more fatty tissue, less water and a different metabolism compared to a male body.
A general guide for staying under the .05 BAC limit is to monitor the number of standard drinks you consume each hour. A standard drink is defined as a drink that contains 10 g of pure alcohol, for example, a 285 mL pot or middy of regular beer (4.9 per cent) is equivalent to a standard drink. For men, it is recommended to have no more than 2 standard drinks in the first hour and no more than one standard drink every hour after to stay under the .05 BAC. For women, it is no more than one standard drink in the first hour and no more than one every hour after that.
For more information, please click on the Australian Drug Foundation's DrugInfo Clearinghouse web site link below.
Last Reviewed: 20 September 2006
