In this post we take a look at the effects of alcohol on driving. We have already discussed some of the long term effects that necessitate imposing legal age limits for alcohol consumption in order to mitigate its neurotoxic effects on the developing brain.
30mg% is the legal blood alcohol concentration (BAC) limit for driving. Limits are a safety requirement to counter the adverse effects of alcohol on driving ability. The 30mg% level is often panned as being too low. Most countries have settled at a 50mg% threshold, some at 20mg%, others (considered very liberal) at 80mg%. Lets take a look at the effects on driving at these various blood alcohol concentrations (CDC 2011).
| BAC | Effect on driving |
|---|---|
| 20mg% | Visual deficits (problems with tracking of a moving object), Decline in multitasking ability (talking to a passenger while driving) |
| 50mg% | Reduced coordination, difficulty steering, increased reaction time for braking by more than a second (Siliquini 2011) |
| 80mg% | Problems with concentration, short term memory loss, reduced information processing capacity, impaired perception |
How long after drinking alcohol is it safe to drive?
You need to wait at least as many hours as the ‘chota pegs’ (1oz or 30ml) you consumed. Alcohol is digested by the liver. The liver has a fixed capacity to metabolise about 8gms of alcohol in an hour. This is the amount of alcohol in 30ml of whisky, vodka, rum or gin. The equivalent dose is 250ml of beer or a glass (150ml) of wine. Each of these is considered as a ‘unit’ of alcohol. However, consuming any quantity of alcohol within 6 hours prior to driving is associated with a doubling of the risk for a road traffic accident (Di Bartolomeo 2009). This effect of alcohol is present even at intake of 1-2 units which works out to a BAC of approximately 50mg%.
Blood alcohol levels as low as 20mg% impair driving ability under test conditions in a simulator. At 50mg% the impairments more than double the risk of an accident. The present 30mg% level may be legal but it remains impairing. Better to have a ‘designated driver’ - the person who does not drink for that particular evening. In case you want to we have already studied how to refuse alcohol.
DONT drink alcohol and driveReferences
- Anthony Burgess. A Clockwork Orange. 1962. (Various publishers including Penguin)
- CDC. http://www.cdc.gov/motorvehiclesafety/pdf/BAC-a.pdf. Accessed 15-Dec-2011.
- Stefano Di Bartolomeo Francesca Valent, Rodolfo Sbrojavacca, Riccardo Marchetti and Fabio Barbone. A case-crossover study of alcohol consumption, meals and the risk of road traffic crashes. BMC Public Health 2009, 9:316 doi:10.1186/1471-2458-9-316
- Roberta Siliquini, Fabrizio Bert, Francisco Alonso, Paola Berchialla, Alessandra Colombo, Axel Druart, Marcin Kedzia, Valeria Siliquini, Daniel Vankov, Anita Villerusa, Lamberto Manzoli and TEN-D Group (TEN-D by Night Group). Correlation between driving-related skill and alcohol use in young-adults from six European countries: the TEN-D by Night Project. BMC Public Health 2011, 11:526 doi:10.1186/1471-2458-11-526.
