Instead of confusing people with units and limits etc , why not just say no Alcohol when in charge of a motor vechicle that to include anything with a engine. Lets face it if you worked on a  prodution line or incharge of machinery at work and you turned up smelling of booze you would be sent home. Also you probably know someone like this has half a pint and there drunk , where as theres people who can drink 10 pints and not be affected in other words everyone has there own limits. The safest limit is 0 Alcohol !

PAul.

Because to many people die each years as a result of drink driving and costs the country allot of money.