There is a new permitted blood alcohol concentration since 1 July 2008 which is 0.3 ppm. All what above are different levels of intoxication:
0.3 - 0.5 - insignificant effect of alcohol
0.5 - 1.5 - mild intoxication
1.5 - 2.5 - moderate intoxication
2.5 - 3.0 - severe intoxication
3.0 - 5.0 - heavy alcohol poisoning
above 5 is considered a deadly dose.
Ppm is a thousandth of a substance or a tenth of a percent, respectively permissible dose of alcohol shall be 0.03% of the fluid in the human body. The fluid is 70% of the total weight of a man or 60% of a woman, respectively, knowing the weight and sex of the person is easy to calculate what would be the concentration of alcohol in his blood.
The maximum concentration of alcohol in blood is achieved approximately 30-120 minutes after drinking, then alcohol gradually begins to "weather". The human body processes alcohol at an average rate of 7-10 grams per hour, knowing this, it's easy to calculate when the blood alcohol concentration again reaches an acceptable level.
Following calculator will help you to know when it's okay to drive after drinking certain beverage:
If there is no certain beverage you can add it to reference Alcohol, which is used in this calculator.