POLICE have warned the only way to be sure of being under the new drink drive limit is "don't risk it".

MSPs on the Scottish Parliament Justice committee asked how people could decide if they were under the limit the morning after, when the limit is cut from 80mg per 100ml of blood to 50mg, on December 8.

A senior officer said police expected to catch around a third more people over the limit as a result of the lower figure, which will be in place for the annual Christmas and New Year drink driving crackdown.

Chief Superintendent Iain Murray said he hoped the public would listen and learn.

He said: "Plan ahead that you can't take the chance. Prioritise aspects of your life, when you drink and when you don't. The simple message is don't risk it. It is not just a legal limit. You are impaired."

Dr Peter Rice, chairman, Scottish Health Action on Alcohol Problems said the only factor in clearing alcohol from the body was time.

Committee convener Christine Grahame asked: "How do you know if you are impaired, how do you know the next morning?"

Dr Rice said someone drinking half a bottle of wine with a meal about 8pm would be clear in the early hours of the morning.

He said: "Nothing speeds that up. Not coffee, a shower, sleep, a full cooked breakfast, nothing. Time is the only thing that clears alcohol from the system."

He was asked how much alcohol the night before would see someone over the limit the next morning.

He said: "Only if you drink pretty substantially the night before. For an eight hour sleep that's about half a bottle of spirits, six pints of beer or a bottle of wine."

Mr Murray added: "The new TV ad will be clear. 'Don't do it'."

stewart.paterson@eveningtimes.co.uk