The amount of alcohol in your body is measured by Blood Alcohol Concentration (BAC).

BAC is determined by the amount of alcohol you drink (more alcohol means higher BAC), how fast you drink (faster drinking means higher BAC), your weight, gender, constitution, individual drinking habits and whether food has been eaten.

The same amount of alcohol consumed will result in different blood alcohol levels for different people.

How does alcohol affect the body?

When you have a drink the alcohol hits your brain within minutes. It starts to slow down and close down your brain’s activity. So your driving skills are quickly impaired. You start to focus more on steering. You miss out on other dangers on the road - like the child about to cross.

How does Alcohol Affect Driving?

All drivers are affected by drinking even small amounts of alcohol. Alcohol affects judgement, vision, co-ordination, and reaction time. It causes serious driving errors, such as:

• Your peripheral vision is affected making it difficult to see signs and other road users, particularly pedestrians and cyclists
• Increased reaction time to hazards
• Driving too fast or too slow
• Driving in the wrong lane
• Running over the kerb
• Weaving
• Quick, jerky starts
• Not signalling, failure to use headlights
• Straddling lanes
• Running stop signs and red lights
• Improper overtaking

Of the eleven functions required to drive, ten are impaired at a BAC level of 0.04. These functions are divided attention, tracking, psychomotor skills, cognitive tasks, choice reaction time, visual function, vigilance, perception and simple reaction time and information (Shiner, 2007).

Read more about:

• Impaired Driving
• Some facts on alcohol & driving